本文介绍了绘制多个矩形Android画布的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试在画布上绘制4个矩形,以便将画布分为4个相等的矩形.使用我现在拥有的代码,仅绘制代码中的最后一个矩形.
I'm trying to draw 4 rectangles on the canvas so that the canvas is divided in 4 equal rectangles. With the code I now have, only the last rectangle in my code is drawn.
这是我的活动中的代码:
This is the code in my Activity:
protected void onCreate(Bundle savedInstanceState) {
...
setContentView(new MyView(this));
}
public class MyView extends View {
public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
setFocusableInTouchMode(true);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int x = getWidth();
int y = getHeight();
Paint paintTopLeft = new Paint();
paintTopLeft.setStyle(Paint.Style.FILL);
paintTopLeft.setColor(Color.WHITE);
canvas.drawPaint(paintTopLeft);
// Use Color.parseColor to define HTML colors
paintTopLeft.setColor(Color.parseColor("#F44336"));
canvas.drawRect(0,0,x / 2,y / 2,paintTopLeft);
Paint paintTopRight = new Paint();
paintTopRight.setStyle(Paint.Style.FILL);
paintTopRight.setColor(Color.WHITE);
canvas.drawPaint(paintTopRight);
// Use Color.parseColor to define HTML colors
paintTopRight.setColor(Color.parseColor("#2196F3"));
canvas.drawRect(x / 2, 0, x, y / 2, paintTopRight);
}
}
我在做什么错了?
推荐答案
实际上,我只看到用您的代码绘制的两个矩形.但是无论如何,问题在于您正在呼叫 canvas.drawPaint 会用该颜色清除/填充整个画布.因此,您将擦除在绘制最后一个矩形之前已经绘制的所有矩形.
Actually I see only two rectangles that are drawn with your code. But anyway, the problem is that you are calling canvas.drawPaint which clears/fills the complete canvas with that color. So you are erasing all rectangles that have been drawn already just before you draw the last one.
此代码应正常工作:
protected void onCreate(Bundle savedInstanceState) {
...
setContentView(new MyView(this));
}
public class MyView extends View {
public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
setFocusableInTouchMode(true);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int x = getWidth();
int y = getHeight();
Paint paintTopLeft = new Paint();
paintTopLeft.setStyle(Paint.Style.FILL);
paintTopLeft.setColor(Color.WHITE);
//canvas.drawPaint(paintTopLeft); // don't do that
// Use Color.parseColor to define HTML colors
paintTopLeft.setColor(Color.parseColor("#F44336"));
canvas.drawRect(0,0,x / 2,y / 2,paintTopLeft);
Paint paintTopRight = new Paint();
paintTopRight.setStyle(Paint.Style.FILL);
paintTopRight.setColor(Color.WHITE);
// canvas.drawPaint(paintTopRight); // don't do that
// Use Color.parseColor to define HTML colors
paintTopRight.setColor(Color.parseColor("#2196F3"));
canvas.drawRect(x / 2, 0, x, y / 2, paintTopRight);
}
}
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