Java 如何在android中更改画布上的特定矩形颜色?
当我触摸屏幕时,我一直在尝试更改一系列矩形中特定矩形的颜色,但它似乎不起作用,以下是我的代码:Java 如何在android中更改画布上的特定矩形颜色?,java,android,colors,grid,android-canvas,Java,Android,Colors,Grid,Android Canvas,当我触摸屏幕时,我一直在尝试更改一系列矩形中特定矩形的颜色,但它似乎不起作用,以下是我的代码: public Paint blue = new Paint(); RandomColorGen rc; ArrayList<Integer> colors = RandomColorGen.ColorList(5); Random rand = new Random(); int columns = 50; int rows = 50; Rect square[][] = new Rect
public Paint blue = new Paint();
RandomColorGen rc;
ArrayList<Integer> colors = RandomColorGen.ColorList(5);
Random rand = new Random();
int columns = 50;
int rows = 50;
Rect square[][] = new Rect[rows][columns];
public boolean isTouched;
public Canvas canvas;
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
this.canvas = canvas;
for (int x = 0; x < rows; x++) {
for (int y = 0; y < columns; y++) {
square[x][y] = new Rect();
blue.setColor(colors.get(rand.nextInt(colors.size())));
blue.setStyle(Paint.Style.FILL);
square[x][y].set(0, 0, (canvas.getWidth() - 10) / rows,
((canvas.getHeight() - 100) / columns));
square[x][y].offsetTo(x * ((canvas.getWidth() - 10) / rows), y
* ((canvas.getHeight() - 100) / columns));
canvas.drawRect(square[x][y], blue);
}
}
if(isTouched){
blue.setColor(colors.get(rand.nextInt(colors.size())));
blue.setStyle(Paint.Style.FILL);
canvas.save();
canvas.clipRect(square[1][1]);
canvas.drawRect(square[1][1], blue);
canvas.restore();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
isTouched = true;
break;
}
return true;
}
public Paint blue=new Paint();
随机染色剂;
ArrayList colors=RandomColorGen.ColorList(5);
Random rand=新的Random();
int列=50;
int行=50;
矩形[][]=新矩形[行][列];
公共布尔值被触发;
公共画布;
@凌驾
受保护的void onDraw(画布){
super.onDraw(帆布);
this.canvas=画布;
对于(int x=0;x
colors.get()thingy是一个颜色数组列表。我是否采取了错误的方法?在执行onTouch操作后,如何调用绘制函数
OnTouch操作是第一个操作,那么如何调用Paint()函数呢?我刚刚测试了您的代码,它可以工作,但有几个值得一提的注意事项:
- 在绘图期间分配对象是一种非常糟糕的行为(特别是在分配50*50时)!考虑将分配代码移到构造函数,并在“代码”> OnDRAW()/<代码>方法中更改矩形的位置,如果您想要实现与现在相同的行为。
- 您对
的使用不完整,只要用户没有举手,您就需要将isTouched设置为true,具体操作如下:onTouchEvent()
}@Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: isTouched = true; break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: isTouched = false; break; } invalidate(); return true;
- 每次收到触摸事件时,也可以使用
invalidate()