检测触摸位图 [英] Detect touch on bitmap

问题描述

映入眼帘，

有谁我如何去检测时对位图这是一个帆布内的用户presses？

Does anyone how I go about detecting when a user presses on a bitmap which is inside a canvas?

感谢

推荐答案

您应该有一些像这样：

public boolean onTouchEvent(MotionEvent event){
    int action = event.getAction();
    int x = event.getX()  // or getRawX();
    int y = event.getY();

    switch(action){
    case MotionEvent.ACTION_DOWN:
        if (x >= xOfYourBitmap && x < (xOfYourBitmap + yourBitmap.getWidth())
                && y >= yOfYourBitmap && y < (yOfYourBitmap + yourBitmap.getHeight())) {
            //tada, if this is true, you've started your click inside your bitmap
        }
        break;
    }
}

这是一个开始，但你需要处理情况下MotionEvent.ACTION_MOVE 和情况下MotionEvent.ACTION_UP ，以确保你妥善处理用户输入。该的onTouchEvent 方法被调用每次用户：把手指向下，移动手指已经在屏幕上或举起手指。每次事件进行的X和其中，手指是Y坐标。例如，如果你想检查有人窃听你的位图里面，你应该做类似设置一个布尔值，触摸开始ACTION_DOWN位图里面，然后检查ACTION_UP说你还是位图内。

That's a start, but you need to handle case MotionEvent.ACTION_MOVE and case MotionEvent.ACTION_UP to make sure you properly deal with the user input. The onTouchEvent method gets called every time the user: puts a finger down, moves a finger already on the screen or lifts a finger. Each time the event carries the X and Y coordinates of where the finger is. For example if you want to check for someone tapping inside your bitmap, you should do something like set a boolean that the touch started inside the bitmap on ACTION_DOWN, and then check on ACTION_UP that you're still inside the bitmap.

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