Published June 7, 2024 © GPL3+

Wio Paint

This "software only" project does a nice job of showing what the Seeed Wio Terminal can do. A small screen but a functional paint program.

IntermediateFull instructions provided4 hours52

Things used in this project

Hardware components

Seeed Studio Wio Terminal

Seeed Studio Wio Terminal Chassis - Battery (650mAh)

Optional

Software apps and online services

Arduino IDE

Story

There are lots of nice projects that have been created with Seeed's Wio Terminal. With its built-in display and several buttons, it is ready for many projects without any additional hardware.

Seeed Wio Terminal with Optional Battery Pack

So to try out its capabilities for a software only project, I created a paint program. It's not really a serious paint program because the screen is too small and the draw functions are mostly limited to what can be accomplished with the Wio graphics library (a version of the TFT-eSPI graphics library). But it turned into a challenging software project that grew rapidly in complexity as I added new features.

This tutorial is probably more about designing a graphical user interface (GUI) than it is about creating a really serious paint program. I encountered some interesting problems along the way. The cursor in particular presented some challenges!

I have divided this story into two parts. In the first, we discuss how the paint program works - its features and how to use it. In the second part, we will look at some of the software and how some of the features were implemented.

The Wio Paint Program Functionality

Let's start with the buttons and what they do.

The top left button, which Wio calls button C, rotates through the eleven preset colors. Everything drawn with red selected, as shown in the drawing, will be red.

The middle top button rotates through the function options shown on the right. The one selected in the picture draws a single pixel. The one below it draws a line. The one below that a square, then a filled square, a rectangle, a filled rectangle, a circle, and a filled circle. The last one in purple erases everything and clears the display.

The top right button, which Wio calls button A, selects and rotates through the line widths which are shown graphically by the line in the bottom right corner. The options are 1 pixel, 3 pixels, 5 pixels or 7 pixels. This setting applies to the point, the line, and the unfilled square, rectangle, and circle.

The Wio 5 way switch (joystick) in the lower right corner moves the cursor around, and draws the selected shape when the set button is pressed. For lines, squares, rectangles and circles, the first Set stores the cursor location, which may be the beginning of a line or the center of a circle. Then you move the cursor to a second location, which may be the end of the line or the radius of the circle. Then pressing Set a second time draws the selected shape.

The image above shows the resulting objects that can be drawn. We have lines and dots of different width depending on the line width setting. We also have both filled and unfilled squares, rectangles, and circles. Squares, by the way, are rectangles where the longer side is forced equal to the shorter side, so pick the starting point, pick the side length, then make the last side any longer length.

There is one other function that I haven't mentioned yet. An "Undo" function is initiated by holding down the color select and linewidth select buttons (the two outside buttons) simultaneously for about 1 second. This will "undo" or erase the last item drawn. (It only works once - no multiple undo's.)

As I said earlier, the graphics functions in my paint program are fairly limited. However, with a little extra work and some patience, you can create anything you want on the screen. Some examples are shown in the image above.

The Wio Paint Program Software

In trying to explain how this all works, it's hard to know where to start. Let's first cover some of the basics, and then go through a list of specific tasks that need to be addressed. I will also list some things I could have implemented, but didn't - this simple program was just getting too complicated.

The basic operation of our paint program consists of putting menus on the screen and using the buttons with those menus to form a graphical user interface. Then we use that GUI to control the graphics library and draw various graphics on the screen. That's all we are doing!

The Wio has a built-in 320 x 240 pixel color display. The TFT-eSPI graphics library controls this display. It places graphics (and text, though we are not using any here) directly onto the display. The content of the display screen is stored in the display's memory, not in our microcontroller's memory, Each pixel (there are 76, 800 of them) has a 16 bit (RGB565) color associated with it.

The graphics library gives us direct access to the display's memory: screen.drawPixel allows us to store a color at that pixel, while screen.readPixel let's us see what color is already stored there. While the graphics library has much more sophisticated commands like screen.fillCircle or screen.drawRectangle, these primitives are super important when you start dealing with a blinking cursor and what screen content is underneath that cursor!

The Cursor

We need a blinking cursor to show us where we are on the screen, but it turns out to be a major complication. We need to make it blink in the main loop, but we also need the main loop to continuously monitor the switches. So we use millis() to time the blinking (instead of delay), while monitoring the buttons.

Moving the cursor with the joystick control moves the cursor 1 pixel at a time, which can be incredibly slow if you are moving across the screen. So if the cursor move button is held down longer that 1/4th second, it switches into rapid-fire mode, where the cursor is advanced every 25 msec. until the button is released.

The cursor needs to be big enough to see clearly, so I made it 3 x 3 pixels. But when the cursor is on, it overwrites the content on the display that was under it. So before turning on the cursor, we must read and save the 9 pixels under the cursor, and then, when we turn off the cursor, we must restore those 9 pixels to their original content. And whenever we move the cursor, we must restore the content under it, then move, then save the content under the cursor in the new location, then display the cursor!

We also need to restore the content under the cursor (frequently in two different places) before creating a new graphic like a circle or rectangle. (Otherwise, if we restore under the cursor after the new graphic is created, the part of it under the cursor will be missing!) Dealing with the cursor turned out to be a major portion of our code!

The Switches

Mechanical switches need to be de-bounced. Wio's example sketches demonstrate using its switches with a 200 msec. delay after pressing a button, but that is not a valid solution. I use a Boolean variable called buttonEnable. It must be true for any button push to be recognized. When any button is pressed, the first thing that happens is that buttonEnable is turned false. The button then does what is intended and then waits until the button is released. Only then, after button release, is buttonEnable returned to true. This approach prevents any switch bounce and its unintended consequences.

Undo Function

As we have already said, the content on the display is stored in the display's memory. Implementing "undo" is similar to dealing with the area under the cursor. We must save the portion of the screen where a new graphic is about to be placed. That is done in the microcontroller's RAM memory. Then we put the new graphic into the display. If we then change our mind and want to "undo" the new graphic, we put the image we stored in RAM back into the display.

At first I tried to keep this simple by storing the entire display's content in RAM. But that proved problematic - while there is more than enough RAM to do that, the screen.readPixel graphic instruction is pretty slow, and storing the entire image on the display caused a noticeable 1-2 second delay. So we find the rectangular area affected by the new graphic, then only store and retrieve that limited area to implement our "undo".

Line Width

The Wio version of the TFT-eSPI graphics library draws objects with a 1 pixel wide line. Adding line width to rectangles and circles was very straight forward - just requiring that we drawing multiple rectangles or circles.

But to draw a line multiple pixels wide between two random points required some work. The screen.drawWideLine function isn't implemented, or if it is, I couldn't find it.

The problem is that what needs to be drawn, besides the single pixel wide line between the two points, is dependent on the slope of the line. I finally settled on a solution that is far from perfect but at least keeps things fairly simple. I calculate the slope of the line (actually its absolute value). If it is less than 0.5, I add the required line width only in the y or vertical direction. If the slope is above 2, I add the required width only in the x or horizontal direction. If between 0.5 and 2, the required line width is added in both directions. Again, not perfect, but seems to work reasonably well.

Potential Additions

There are two things I did not implement, which might have been nice additions.

The first is a generic fill routine (which can fill any random shaped area of one color with a different color. This is accomplished with a recursive algorithm called Flood Fill. It could be implemented on this system, but would have added a lot of extra coding.

The other nice feature I did not implement was a basic version of cut, copy and paste. Again, these would be fairly straight forward additions, but I think this project already got complicated enough!

Wio Paint

#include "SPI.h"
#include "TFT_eSPI.h"

TFT_eSPI screen = TFT_eSPI();  // TFT graphic object instance

#define TFT_AQUA 0x07FF  // add these colors to stardard palatte 
#define TFT_DARK_ORANGE 0xFC60
#define TFT_BROWN 0xA145
#define TFT_GREY 0xAD55

const uint16_t colors[11] = {TFT_RED, TFT_DARK_ORANGE, TFT_YELLOW, TFT_GREEN,
                       TFT_AQUA, TFT_BLUE, TFT_MAGENTA, TFT_BROWN,
                       TFT_GREY, TFT_WHITE, TFT_BLACK
                      };
// global variables                      
uint16_t myColor = TFT_RED;
int colorChoice = 0;  // index of selected color
int cursorX = 27, cursorY = 1;  // current location of the cursor
int myX, myY;  // previous location of cursor
uint16_t underCursor[3][3] = {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}; // for current cursor
uint16_t underCursor2[3][3] = {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}};  // for previous cursor
uint16_t myScreen[320][240] = {0}; // used for "undo" only
long myTime; // used with millis() to blink the cursor
int cursorStatus = 0;  // controls preserving screen content under the cursor
int myFunction = 8;  // index of selected function
int widthCount = 3;  // index of selected line width
bool buttonEnable = true;  // are buttons active?
bool pointSet = false;  // has the first cursor position been set?
int xx1,xx2,yy1,yy2; // creates the area to store for the "undo" function
int xMin, yMin, xLen, yLen;  // used to properly configure rectangles and squares

void setup() {
  Serial.begin(9600);
  // enable the buttons
  pinMode(WIO_5S_UP, INPUT_PULLUP);
  pinMode(WIO_5S_DOWN, INPUT_PULLUP);
  pinMode(WIO_5S_LEFT, INPUT_PULLUP);
  pinMode(WIO_5S_RIGHT, INPUT_PULLUP);
  pinMode(WIO_5S_PRESS, INPUT_PULLUP);
  pinMode(WIO_KEY_A, INPUT_PULLUP);
  pinMode(WIO_KEY_B, INPUT_PULLUP);
  pinMode(WIO_KEY_C, INPUT_PULLUP);
  screen.init();
  screen.setRotation(3);
  initialize();  // clear the screen and set up menus
}  // end of setup

// Main loop does two things: blink the cursor and monitor the buttons
void loop() {
  if (cursorStatus == 0 ) {
    saveUnderCursor(cursorX, cursorY);
    cursorStatus = 1;
    if (myColor == TFT_BLACK) screen.fillRect(cursorX - 1, cursorY - 1, 3, 3, TFT_WHITE);
    else screen.fillRect(cursorX - 1, cursorY - 1, 3, 3, myColor);
  }
  if (millis() > myTime + 499 && cursorStatus == 1) {
    displayUnderCursor(cursorX, cursorY);
    cursorStatus = 2;
  }
  if (millis() > myTime + 999) {
    myTime = millis();
    cursorStatus = 0;
  }

  if (buttonEnable = true && digitalRead(WIO_5S_UP) == LOW) {
    buttonEnable = false;
    if (cursorY > 1) moveCursor(cursorX, cursorY - 1);
    delay(250);
    while (digitalRead(WIO_5S_UP) == LOW) {
      if (cursorY > 1) moveCursor(cursorX, cursorY - 1);
    }
  }
  else if (buttonEnable = true && digitalRead(WIO_5S_DOWN) == LOW) {
    buttonEnable = false;
    if (cursorY < 236)moveCursor(cursorX, cursorY + 1);
    delay(250);
    while (digitalRead(WIO_5S_DOWN) == LOW) {
      if (cursorY < 236)moveCursor(cursorX, cursorY + 1);
    }
  }
  else if (buttonEnable = true && digitalRead(WIO_5S_LEFT) == LOW) {
    buttonEnable = false;
    if (cursorX > 27)moveCursor(cursorX - 1, cursorY);
    delay(250);
    while (digitalRead(WIO_5S_LEFT) == LOW) {
      if (cursorX > 27)moveCursor(cursorX - 1, cursorY);
    }

  }
  else if (buttonEnable = true && digitalRead(WIO_5S_RIGHT) == LOW) {
    buttonEnable = false;
    if (cursorX < 286)moveCursor(cursorX + 1, cursorY);
    delay(250);
    while (digitalRead(WIO_5S_RIGHT) == LOW) {
      if (cursorX < 286)moveCursor(cursorX + 1, cursorY);
    }
  }
  // PRESS FUNCTION
  else if (buttonEnable = true && digitalRead(WIO_5S_PRESS) == LOW) {
    buttonEnable = false;
    if (myFunction == 0) draw_Dot();
    else if (myFunction == 1) draw_Line();
    else if (myFunction == 2) draw_Square();
    else if (myFunction == 3) fill_Square();
    else if (myFunction == 4) draw_Rectangle();
    else if (myFunction == 5) fill_Rectangle();
    else if (myFunction == 6) draw_Circle();
    else if (myFunction == 7) fill_Circle();
    else if (myFunction == 8) initialize();

    while (digitalRead(WIO_5S_PRESS) == LOW) {}
  }
  else if (buttonEnable = true && digitalRead(WIO_KEY_C) == LOW) { // select color
    buttonEnable = false;
    delay(250);
    if (digitalRead(WIO_KEY_A) == LOW) {
      retrieveScreen(xx1,yy1,xx2,yy2);  // Undo function when buttons A and C are both pushed
    }
    else advanceColor();
    while (digitalRead(WIO_KEY_C) == LOW) {}
  }
  else if (buttonEnable = true && digitalRead(WIO_KEY_B) == LOW) { // select color
    buttonEnable = false;
    advanceFunction();
    while (digitalRead(WIO_KEY_B) == LOW) {}
  }
  else if (buttonEnable = true && digitalRead(WIO_KEY_A) == LOW) {
    buttonEnable = false;
    delay(250);
    if (digitalRead(WIO_KEY_C) == LOW) {
      retrieveScreen(xx1,yy1,xx2,yy2);   // Undo function when buttons A and C are both pushed
    }
    else advanceLineWidth();
    while (digitalRead(WIO_KEY_A) == LOW) {}
  }
  buttonEnable = true;
} // end of loop

// set up color palette
void colorMenu() {
  screen.fillRect(0, 1, 18, 18, TFT_RED);
  screen.fillRect(0, 21, 18, 18, TFT_DARK_ORANGE);
  screen.fillRect(0, 41, 18, 18, TFT_YELLOW);
  screen.fillRect(0, 61, 18, 18, TFT_GREEN);
  screen.fillRect(0, 81, 18, 18, TFT_AQUA);
  screen.fillRect(0, 101, 18, 18, TFT_BLUE);
  screen.fillRect(0, 121, 18, 18, TFT_MAGENTA);
  screen.fillRect(0, 141, 18, 18, TFT_BROWN);
  screen.fillRect(0, 161, 18, 18, TFT_GREY);
  screen.fillRect(0, 181, 18, 18, TFT_WHITE);
  screen.drawRect(0, 201, 18, 18, TFT_WHITE);
}

void advanceColor() {
  screen.fillRect(20, colorChoice * 20 + 1, 4, 18, TFT_WHITE);
  if (colorChoice > 0) screen.fillRect(20, colorChoice * 20 - 19, 4, 18, TFT_BLACK);
  else screen.fillRect(20, 201, 4, 18, TFT_BLACK);
  myColor = colors[colorChoice];
  colorChoice ++;
  if (colorChoice > 10) colorChoice = 0;
}

//set up the function menu
void functionMenu() {
  screen.drawRect(298, 1, 20, 20, TFT_WHITE);
  screen.drawRect(300, 3, 16, 16, TFT_BLACK);
  screen.fillRect(306, 10, 2, 2, TFT_YELLOW); // point
  screen.drawRect(298, 21, 20, 20, TFT_WHITE);
  screen.drawRect(300, 23, 16, 16, TFT_BLACK);
  screen.fillRect(302, 30, 12, 2, TFT_YELLOW); // line
  screen.drawRect(298, 41, 20, 20, TFT_WHITE);
  screen.drawRect(300, 43, 16, 16, TFT_BLACK);
  screen.drawRect(305, 48, 6, 6, TFT_YELLOW); // draw square
  screen.drawRect(298, 61, 20, 20, TFT_WHITE);
  screen.drawRect(300, 63, 16, 16, TFT_BLACK);
  screen.fillRect(305, 68, 6, 6, TFT_YELLOW); // fill square
  screen.drawRect(298, 81, 20, 20, TFT_WHITE);
  screen.drawRect(300, 83, 16, 16, TFT_BLACK);
  screen.drawRect(302, 88, 12, 6, TFT_YELLOW); // draw rectangle
  screen.drawRect(298, 101, 20, 20, TFT_WHITE);
  screen.drawRect(300, 103, 16, 16, TFT_BLACK);
  screen.fillRect(302, 108, 12, 6, TFT_YELLOW); // fill rectangle
  screen.drawRect(298, 121, 20, 20, TFT_WHITE);
  screen.drawRect(300, 123, 16, 16, TFT_BLACK);
  screen.drawCircle(308, 130, 5, TFT_YELLOW); // draw circle
  screen.drawRect(298, 141, 20, 20, TFT_WHITE);
  screen.drawRect(300, 143, 16, 16, TFT_BLACK);
  screen.fillCircle(308, 150, 5, TFT_YELLOW); // fill circle
  screen.drawRect(298, 161, 20, 20, TFT_WHITE);
  screen.fillRect(300, 163, 16, 16, TFT_MAGENTA);
}

void advanceFunction() {
  myFunction ++;
  if (myFunction > 8) myFunction = 0;
  screen.fillRect(292, myFunction * 20 + 1, 4, 18, TFT_WHITE);
  if (myFunction > 0) screen.fillRect(292, myFunction * 20 - 19, 4, 18, TFT_BLACK);
  else screen.fillRect(292, 161, 4, 18, TFT_BLACK);
  pointSet = false;
}

//set up the line width menu
void lineWidthMenu() {
  screen.drawRect(298, 191, 20, 30, TFT_WHITE);
  screen.fillRect(300, 193, 16, 26, TFT_BLACK);
  screen.drawLine(308, 195, 308, 217, TFT_YELLOW);
}

void advanceLineWidth() {
  widthCount ++;
  if (widthCount > 3) widthCount = 0;
  if (widthCount == 0) screen.fillRect(300, 193, 16, 26, TFT_BLACK);
  screen.fillRect(308 - widthCount, 195, widthCount * 2 + 1, 22, TFT_YELLOW);
}

// moves the cursor to a new position, restoring content under the cursor in its old position
void moveCursor(int curX, int curY) {
  displayUnderCursor(cursorX, cursorY);  // put content under the cursor on the display
  saveUnderCursor(curX, curY);  // save the content on the display in the new cursor position
  cursorX = curX; cursorY = curY; // set cursor to its new position
  // show the cursor in its new position for 25 msec.
  if (myColor == TFT_BLACK) screen.fillRect(cursorX - 1, cursorY - 1, 3, 3, TFT_WHITE);
  else screen.fillRect(cursorX - 1, cursorY - 1, 3, 3, myColor);
  delay(25);
  // then put the content under the cursor back on the display
  displayUnderCursor(cursorX, cursorY);
}

// stores a portion of the screen content in support of UNDO
void saveScreen(int xx3, int yy3, int xx4, int yy4) {
  displayUnderCursor(cursorX, cursorY);
  for (int x = xx3; x < xx4+1; x++) {
    for (int y = yy3; y < yy4+1; y++) {
      myScreen[x][y] = screen.readPixel(x, y);
    }
  }
}

// retrieves a previously saved postion of the screen in support of UNDO
void retrieveScreen(int xx3, int yy3, int xx4, int yy4) {
  for (int x = xx3; x < xx4+1; x++) {
    for (int y = yy3; y < yy4+1; y++) {
      screen.drawPixel(x, y, myScreen[x][y]);
    }
  }
}

// fresh start - clear the entire screen, set up all the menus, initiallize key variables
void initialize() {
  screen.fillScreen(TFT_BLACK);
  myColor = TFT_RED;
  cursorStatus = 0;
  colorChoice = 0;
  myFunction = 8;
  widthCount = 0;
  myTime = millis();
  colorMenu();
  advanceColor();
  functionMenu();
  advanceFunction();
  lineWidthMenu();
  advanceLineWidth();
  cursorX = 27; cursorY = 1;
  pointSet = false;
}

// for most graphics, two points are needed - this setup up the first point
// it marks that position, but first save the content under the cursor.
void setFirstPoint() {
  myX = cursorX;
  myY = cursorY; 
  displayUnderCursor(cursorX, cursorY);
  saveUnderCursor2(cursorX, cursorY);
  screen.fillRect(cursorX-1, cursorY-1, 3, 3, myColor);
  cursorX += 6;
  pointSet = true;
}

// draws a dot, the size of which is determined by line width setting
void draw_Dot() {
  xx1 = cursorX-3; yy1= cursorY-3;  xx2 = cursorX+3; yy2= cursorY+3;
  saveScreen(xx1,yy1,xx2,yy2);  // save for undo
  displayUnderCursor(cursorX - 1, cursorY - 1);
  if (widthCount > 2) screen.fillRect(cursorX - 3, cursorY - 3, 7, 7, myColor);
  else if (widthCount > 1) screen.fillRect(cursorX - 2, cursorY - 2, 5, 5, myColor);
  else if (widthCount > 0) screen.fillRect(cursorX - 1, cursorY - 1, 3, 3, myColor);
  else screen.drawPixel(cursorX, cursorY, myColor);
  saveUnderCursor(cursorX, cursorY);
}

// draws a line, the width of which is approximately determined by the line width setting
void draw_Line() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    xx1 = myX; yy1 = myY;  
    xx2 = cursorX; yy2 = cursorY;
    // for undo function, we need to get boundries in proper order
    // xx1 must be less than xx2, yy1 must be less that yy2
    // and they must take line width into account
    if (xx2 < xx1) {
      int temp = xx2;
      xx2 = xx1;
      xx1 = temp;    
    }
    if (yy2 < yy1) {
      int temp = yy2;
      yy2 = yy1;
      yy1 = temp;    
    }
    xx1 -= 4 ; yy1 -= 4; xx2 += 4; yy2 += 4;
    saveScreen(xx1,yy1,xx2,yy2);  // save for undo
    screen.drawLine(myX, myY, cursorX, cursorY, myColor);
    float slope = (float)abs(myY - cursorY) / (float)abs(myX - cursorX);
    if (widthCount > 0) {
      if (slope > 0.5) {
        screen.drawLine(myX - 1, myY, cursorX - 1, cursorY, myColor);
        screen.drawLine(myX + 1, myY, cursorX + 1, cursorY, myColor);
      }
      if (slope < 2) {
        screen.drawLine(myX, myY - 1, cursorX, cursorY - 1, myColor);
        screen.drawLine(myX, myY + 1, cursorX, cursorY + 1, myColor);
      }
    }
    if (widthCount > 1) {
      if (slope > 0.5) {
        screen.drawLine(myX - 2, myY, cursorX - 2, cursorY, myColor);
        screen.drawLine(myX + 2, myY, cursorX + 2, cursorY, myColor);
      }
      if (slope < 2) {
        screen.drawLine(myX, myY - 2, cursorX, cursorY - 2, myColor);
        screen.drawLine(myX, myY + 2, cursorX, cursorY + 2, myColor);
      }
    }
    if (widthCount > 2) {
      if (slope > 0.5) {
        screen.drawLine(myX - 3, myY, cursorX - 3, cursorY, myColor);
        screen.drawLine(myX + 3, myY, cursorX + 3, cursorY, myColor);
      }
      if (slope < 2) {
        screen.drawLine(myX, myY - 3, cursorX, cursorY - 3, myColor);
        screen.drawLine(myX, myY + 3, cursorX, cursorY + 3, myColor);
      }
    }
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// find the minX, minY, xLen,and yLen of a square given any two opposite corners
// cleans up the dimensions of a square, regardless of how user defined it.
void fixXYsqr(int myX1, int myY1, int cursorX1, int cursorY1){
  int sqrSize = abs(myX1 - cursorX1);
  if (abs(myY1 - cursorY1) < sqrSize) sqrSize = abs(myY1 - cursorY1);
  if (myX1 < cursorX1) xMin = myX1; 
  else xMin = myX1-sqrSize;
  xLen = sqrSize; 
  if (myY1 < cursorY1) yMin = myY1; 
  else yMin = myY1-sqrSize;
  yLen = sqrSize; 
}

//  draw the outline of a square with line width set by line width menu
void draw_Square() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    fixXYsqr(myX, myY, cursorX, cursorY);
    int sqrSize = abs(myX - cursorX);
    if (abs(myY - cursorY) < sqrSize) sqrSize = abs(myY - cursorY);
    xx1 = xMin-3; yy1 = yMin-3; xx2 = xMin+sqrSize+3; yy2 = yMin+sqrSize+3;
    saveScreen(xx1,yy1,xx2,yy2);  // save for Undo
    screen.drawRect(xMin, yMin, sqrSize, sqrSize, myColor);
    if (widthCount > 0) {
      screen.drawRect(xMin - 1, yMin - 1, sqrSize + 2, sqrSize + 2, myColor);
      screen.drawRect(xMin + 1, yMin + 1, sqrSize - 2, sqrSize - 2, myColor);
    }
    if (widthCount > 1) {
      screen.drawRect(xMin - 2, yMin - 2, sqrSize + 4, sqrSize + 4, myColor);
      screen.drawRect(xMin + 2, yMin + 2, sqrSize - 4, sqrSize - 4, myColor);
    }
    if (widthCount > 2) {
      screen.drawRect(xMin - 3, yMin - 3,  sqrSize + 6, sqrSize + 6, myColor);
      screen.drawRect(xMin + 3, yMin + 3, sqrSize - 6, sqrSize - 6, myColor);
    }
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// draw a filled in square
void fill_Square() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    fixXYsqr(myX, myY, cursorX, cursorY);
    int sqrSize = abs(myX - cursorX);
    if (abs(myY - cursorY) < sqrSize) sqrSize = abs(myY - cursorY);
    xx1 = xMin; yy1 = yMin; xx2 = xMin+sqrSize; yy2 = yMin+sqrSize;
    saveScreen(xx1,yy1,xx2,yy2);
    screen.fillRect(xMin, yMin, sqrSize, sqrSize, myColor);
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// find the minX, minY, xLen,and yLen of a rectangle given any two opposite corners
// cleans up the dimensions of a rectangle, regardless of how user defined it.
void fixXYrect(int myX1, int myY1, int cursorX1, int cursorY1){
  if (myX1 < cursorX1) xMin = myX1; 
  else xMin = cursorX1;
  xLen = abs(cursorX1-myX1); 
  if (myY1 < cursorY1) yMin = myY1; 
  else yMin = cursorY1;
  yLen = abs(cursorY1-myY1); 
}

//  draw the outline of a rectangle with line width set by line width menu
void draw_Rectangle() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    fixXYrect(myX, myY, cursorX, cursorY);
    xx1 = xMin-3; yy1 = yMin-3; xx2 = xMin+xLen+3; yy2 = yMin+yLen+3;
    saveScreen(xx1,yy1,xx2,yy2);
    screen.drawRect(xMin, yMin, xLen, yLen, myColor);
    if (widthCount > 0) {
      screen.drawRect(xMin - 1, yMin - 1, xLen + 2, yLen + 2, myColor);
      screen.drawRect(xMin + 1, yMin + 1, xLen - 2, yLen - 2, myColor);
    }
    if (widthCount > 1) {
      screen.drawRect(xMin - 2, yMin - 2, xLen + 4, yLen + 4, myColor);
      screen.drawRect(xMin + 2, yMin + 2, xLen - 4, yLen - 4, myColor);
    }
    if (widthCount > 2) {
      screen.drawRect(xMin - 3, yMin - 3, xLen + 6, yLen + 6, myColor);
      screen.drawRect(xMin + 3, yMin + 3, xLen - 6, yLen - 6, myColor);
    }
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// draw a filled in rectangle
void fill_Rectangle() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX - 1, myY - 1);
    displayUnderCursor(cursorX, cursorY);
    fixXYrect(myX, myY, cursorX, cursorY);
    xx1 = xMin; yy1 = yMin; xx2 = xMin+xLen; yy2 = yMin+yLen;
    saveScreen(xx1,yy1,xx2,yy2);  // save for undo
    screen.fillRect(xMin, yMin, xLen, yLen, myColor);
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

//  draw the outline of a circle with line width set by line width menu
void draw_Circle() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    int myRadius = sqrt(((cursorX - myX) * (cursorX - myX)) + 
                   ((cursorY - myY) * (cursorY - myY)));
    xx1 = myX - myRadius - 3; yy1 = myY - myRadius - 3;  
    xx2 = myX + myRadius + 3; yy2 = myY + myRadius + 3;
    saveScreen(xx1,yy1,xx2,yy2); // save for undo
    screen.drawCircle(myX, myY, myRadius, myColor);
    if (widthCount > 0) {
      screen.drawCircle(myX, myY, myRadius - 1, myColor);
      screen.drawCircle(myX, myY, myRadius + 1, myColor);
    }
    if (widthCount > 1) {
      screen.drawCircle(myX, myY, myRadius - 2, myColor);
      screen.drawCircle(myX, myY, myRadius + 2, myColor);
    }
    if (widthCount > 2) {
      screen.drawCircle(myX, myY, myRadius - 3, myColor);
      screen.drawCircle(myX, myY, myRadius + 3, myColor);
    }
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// draw a filled in circle
void fill_Circle() {
  if (pointSet == false) {
    setFirstPoint();
    return;
  }
  else {
    displayUnderCursor2(myX, myY);
    displayUnderCursor(cursorX, cursorY);
    int myRadius = sqrt(((cursorX - myX) * (cursorX - myX)) + 
                   ((cursorY - myY) * (cursorY - myY)));
    xx1 = myX - myRadius; yy1 = myY - myRadius;  
    xx2 = myX + myRadius; yy2 = myY + myRadius;
    saveScreen(xx1,yy1,xx2,yy2); // save for undo
    screen.fillCircle(myX, myY, myRadius, myColor);
    pointSet = false;
    saveUnderCursor(cursorX, cursorY);
  }
}

// put saved content under the cursor back onto the display
void displayUnderCursor(int curX, int curY) {
  // restore old content from under the cursor
  screen.drawPixel(curX - 1, curY - 1, underCursor[0][0]);
  screen.drawPixel(curX,   curY - 1, underCursor[1][0]);
  screen.drawPixel(curX + 1, curY - 1, underCursor[2][0]);
  screen.drawPixel(curX - 1, curY  , underCursor[0][1]);
  screen.drawPixel(curX  , curY  , underCursor[1][1]);
  screen.drawPixel(curX + 1, curY  , underCursor[2][1]);
  screen.drawPixel(curX - 1, curY + 1, underCursor[0][2]);
  screen.drawPixel(curX  , curY + 1, underCursor[1][2]);
  screen.drawPixel(curX + 1, curY + 1, underCursor[2][2]);
}

// save the content under the cursor before displaying cursor
void saveUnderCursor(int curX, int curY) {
  // save new content under the cursor
  underCursor[0][0] = screen.readPixel(curX - 1, curY - 1);
  underCursor[1][0] = screen.readPixel(curX  , curY - 1);
  underCursor[2][0] = screen.readPixel(curX + 1, curY - 1);
  underCursor[0][1] = screen.readPixel(curX - 1, curY  );
  underCursor[1][1] = screen.readPixel(curX  , curY  );
  underCursor[2][1] = screen.readPixel(curX + 1, curY  );
  underCursor[0][2] = screen.readPixel(curX - 1, curY + 1);
  underCursor[1][2] = screen.readPixel(curX  , curY + 1);
  underCursor[2][2] = screen.readPixel(curX + 1, curY + 1);
}

// display content that was under the first point marked for a new graphic
void displayUnderCursor2(int curX, int curY) {
  // restore old content from under the cursor
  screen.drawPixel(curX - 1, curY - 1, underCursor2[0][0]);
  screen.drawPixel(curX,   curY - 1, underCursor2[1][0]);
  screen.drawPixel(curX + 1, curY - 1, underCursor2[2][0]);
  screen.drawPixel(curX - 1, curY  , underCursor2[0][1]);
  screen.drawPixel(curX  , curY  , underCursor2[1][1]);
  screen.drawPixel(curX + 1, curY  , underCursor2[2][1]);
  screen.drawPixel(curX - 1, curY + 1, underCursor2[0][2]);
  screen.drawPixel(curX  , curY + 1, underCursor2[1][2]);
  screen.drawPixel(curX + 1, curY + 1, underCursor2[2][2]);
}

// save the screen content under the cursor before marking first point for a new graphic
void saveUnderCursor2(int curX, int curY) {
  // save new content under the cursor
  underCursor2[0][0] = screen.readPixel(curX - 1, curY - 1);
  underCursor2[1][0] = screen.readPixel(curX  , curY - 1);
  underCursor2[2][0] = screen.readPixel(curX + 1, curY - 1);
  underCursor2[0][1] = screen.readPixel(curX - 1, curY  );
  underCursor2[1][1] = screen.readPixel(curX  , curY  );
  underCursor2[2][1] = screen.readPixel(curX + 1, curY  );
  underCursor2[0][2] = screen.readPixel(curX - 1, curY + 1);
  underCursor2[1][2] = screen.readPixel(curX  , curY + 1);
  underCursor2[2][2] = screen.readPixel(curX + 1, curY + 1);
}

Credits

Doug Domke

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Wio Paint

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Wio Paint

Wio Paint

Things used in this project

Hardware components

Software apps and online services

Story

The Wio Paint Program Functionality

The Wio Paint Program Software

Code

Wio Paint

Credits

Doug Domke

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