绘制正方形时按键问题 [英] Problem with keypressed when drawing a square

问题描述

我试图在按下鼠标键时向画布添加一个正方形，我希望它在松开鼠标键时保留在画布上，但在松开键时它消失.任何人都可以帮助我，我做错了什么?

int squareSize = 6;最终浮点 DIFF_SIZE = 1;最终 int MIN_COLOUR = 1;最终 int MAX_COLOUR = 10;最终浮点数 INIT_RED = 100，INIT_GREEN = 50，INIT_BLUE = 80；最终浮动 FINAL_RED = 255, FINAL_GREEN = 200, FINAL_BLUE = 250;最终浮动 MAX_SIZE = 40;最终浮动 X_SPACING = 10;最终浮动 Y_SPACING = 10;浮动squareX，squareY；无效设置(){大小(600, 600);}无效画(){squareX = mouseX - squareSize/2;squareY = mouseY - squareSize/2;背景(255)；drawRowsOfBlocks();}无效 drawOneBlock() {rect(squareX，squareY，squareSize，squareSize)；for (int i = MIN_COLOUR; mousePressed && i <= MAX_COLOUR/10; i++){float redValue = INIT_RED + (i - MIN_COLOUR)/(MAX_COLOUR - MIN_COLOUR)(FINAL_RED - INIT_RED);float greenValue = INIT_GREEN + (i - MIN_COLOUR)/(MAX_COLOUR - MIN_COLOUR)(FINAL_GREEN - INIT_GREEN);float blueValue = INIT_BLUE + (i - MIN_COLOUR)/(MAX_COLOUR - MIN_COLOUR) * (FINAL_BLUE - INIT_BLUE);填充(红色值，绿色值，蓝色值)；rect(squareX，squareY，squareSize，squareSize)；squareSize += DIFF_SIZE;}如果 (squareSize > MAX_SIZE) {平方大小 = 6;}}无效 drawRowsOfBlocks() {drawOneBlock();for (int i = 1; keyPressed && i <= 2; i++) {drawOneBlock();浮动平方Y2；squareY2 = squareY + squareSize + Y_SPACING;平方Y = 平方Y2；}}

解决方案

创建一个可以处理矩形的类.调用需要一个绘制矩形的方法(Draw())和一个更新矩形位置和大小的方法(Update()):

final int DIFF_SIZE = 1;最终 int MIN_SIZE = 6;最终 int MAX_SIZE = 40;最终浮点数 INIT_RED = 100，INIT_GREEN = 50，INIT_BLUE = 80；最终浮动 FINAL_RED = 255, FINAL_GREEN = 200, FINAL_BLUE = 250;类矩形{int pos_x，pos_y，大小；颜色颜色;矩形(int px，int py，int s，颜色c){列 = c;pos_x = px;pos_y = py;大小 = s;}无效更新(int px，int py，int inc_size){pos_x = px;pos_y = py;大小 += inc_size;如果(大小 > MAX_SIZE)大小 = MIN_SIZE;float w = float(size - MIN_SIZE)/float(MAX_SIZE - MIN_SIZE);float redValue = INIT_RED + w * (FINAL_RED - INIT_RED);float greenValue = INIT_GREEN + w * (FINAL_GREEN - INIT_GREEN);float blueValue = INIT_BLUE + w * (FINAL_BLUE - INIT_BLUE);col = color(int(redValue), int(greenValue), int(blueValue));}无效绘制(){填充(列)；rect(pos_x-size/2，pos_y-size/2，大小，大小)；}}

使用

I am trying to add a square to the canvas when a mouse key is pressed and i want it to remain on the canvas when the mouse key is released, but it disappears when is released the key. Can anybody help me, what am i doing wrong?

int squareSize = 6;
final float DIFF_SIZE = 1;
final int MIN_COLOUR = 1;
final int MAX_COLOUR = 10;
final float INIT_RED = 100, INIT_GREEN = 50, INIT_BLUE = 80;
final float FINAL_RED = 255, FINAL_GREEN = 200, FINAL_BLUE = 250;
final float MAX_SIZE = 40;
final float X_SPACING = 10;
final float Y_SPACING = 10;
float squareX, squareY;
void setup() {
    size(600, 600);
}

void draw() {
    squareX = mouseX - squareSize / 2;
    squareY = mouseY - squareSize / 2;
    background(255);

    drawRowsOfBlocks();

}

void drawOneBlock() {

    rect(squareX, squareY, squareSize, squareSize);
    for (int i = MIN_COLOUR; mousePressed && i <= MAX_COLOUR / 10; i++)

    {
        float redValue = INIT_RED + (i - MIN_COLOUR) / (MAX_COLOUR - MIN_COLOUR)(FINAL_RED - INIT_RED);
        float greenValue = INIT_GREEN + (i - MIN_COLOUR) / (MAX_COLOUR - MIN_COLOUR)(FINAL_GREEN - INIT_GREEN);
        float blueValue = INIT_BLUE + (i - MIN_COLOUR) / (MAX_COLOUR - MIN_COLOUR) * (FINAL_BLUE - INIT_BLUE);
        fill(redValue, greenValue, blueValue);
        rect(squareX, squareY, squareSize, squareSize);
        squareSize += DIFF_SIZE;
    }
    if (squareSize > MAX_SIZE) {
        squareSize = 6;
    }
}

void drawRowsOfBlocks() {
    drawOneBlock();

    for (int i = 1; keyPressed && i <= 2; i++) {
        drawOneBlock();

        float squareY2;
        squareY2 = squareY + squareSize + Y_SPACING;
        squareY = squareY2;
    }
}

解决方案

Create a class which can handle a rectangle. The calls needs a method to draw the rectangle (Draw()) and a method to update the position and size of the rectangle (Update()):

final int DIFF_SIZE = 1;
final int MIN_SIZE = 6;
final int MAX_SIZE = 40;

final float INIT_RED = 100, INIT_GREEN = 50, INIT_BLUE = 80;
final float FINAL_RED = 255, FINAL_GREEN = 200, FINAL_BLUE = 250;

class Rectangle {

    int pos_x, pos_y, size;
    color col;

    Rectangle(int px, int py, int s, color c) {
        col = c;
        pos_x = px; pos_y = py;
        size = s;
    }

    void Update(int px, int py, int inc_size) {
        pos_x = px; pos_y = py;

        size += inc_size;
        if (size > MAX_SIZE)
            size = MIN_SIZE;

        float w = float(size - MIN_SIZE) / float(MAX_SIZE - MIN_SIZE);
        float redValue   = INIT_RED   + w * (FINAL_RED - INIT_RED);
        float greenValue = INIT_GREEN + w * (FINAL_GREEN - INIT_GREEN);
        float blueValue  = INIT_BLUE  + w * (FINAL_BLUE - INIT_BLUE);
        col = color(int(redValue), int(greenValue), int(blueValue));
    }

    void Draw() {
        fill(col);
        rect(pos_x-size/2, pos_y-size/2, size, size);
    }
}

Use ArrayList to store all the drawn rectangles:

ArrayList<Rectangle> rectangles = new ArrayList<Rectangle>();

Add a global, boolean state (drawingRect) which indicates if the mouse button is currently pressed. Set the state and add new rectangle at the end of the list when the mousePressed() event occurs. rest the state when the mouseReleased() event occurs

boolean drawingRect = false;

void mousePressed() {
    drawingRect = true;

    color col = color(int(INIT_RED), int(INIT_GREEN), int(INIT_BLUE));
    rectangles.add(new Rectangle(mouseX, mouseY, MIN_SIZE, col));
}

void mouseReleased() {
    drawingRect = false;
}

Use the method .Update(), to change the location and size of the last rectangle in the list as long as the state drawingRect indicates that a mouse button is pressed.
Continuously draw all te rectangles in a loop:

void setup() {
    size(600, 600);
}

void draw() {

    if (drawingRect && rectangles.size() > 0) {
        Rectangle lastRect = rectangles.get(rectangles.size()-1);
        lastRect.Update(mouseX, mouseY, DIFF_SIZE);
    }

    background(255);

    for (int i = 0; i < rectangles.size(); i++) {
        Rectangle rect = rectangles.get(i);
        rect.Draw();
    }
}

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