我对编程还比较新，对图形编程更是一窍不通。我希望能得到一些指导，因为我找不到我需要的答案。
我有一个扩展视图的类。我在自定义画布上创建了几个三层矩形。我可以成功地触摸和移动每个矩形。我可以平移整个画布。我可以在平移后移动单个矩形。我可以缩放整个屏幕。唯一不能做到的是，在缩放后移动单个矩形。我无法“找到”缩放后的矩形。我已经准备放弃整个自定义视图，并尝试使用imageview或其他我可以控制的东西来完成此操作，而不是通过坐标查看被触摸的内容。
我的问题是：如何找到缩放后矩形的坐标？我的猜测是基于画布的移动或缩放重新计算每个矩形，但很明显我错过了什么，因为这似乎过于复杂，并且对我没有用。
以下是一些代码 - 请原谅混乱，我只是想把思路表达出来。我尝试使用矩阵以及缩放因子进行计算，但是两者都似乎没有让我到达正确的位置。（一些代码没有使用 - 我用了它，但无法正确计算矩形的位置...如果这甚至是正确的方法？）
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.translate(xOffset, yOffset);
canvas.scale(scaleFactor, scaleFactor);
for (RectF r: RectFs){
paint.setStyle(Paint.Style.STROKE);
paint.setColor(Color.BLACK);
canvas.drawRoundRect(r, 20, 20,paint); //Set a border
paintShader.setStyle(Style.FILL);
paintShader.setShader(new LinearGradient(r.left, r.bottom, r.right, r.top, Color.CYAN, Color.YELLOW, Shader.TileMode.REPEAT));
canvas.drawRoundRect(r, 20, 20, paintShader);
paint.setColor(Color.BLACK);
paint.setTextSize(textSize);
paint.setTypeface(Typeface.defaultFromStyle(Typeface.BOLD));
paint.setLinearText(true);
canvas.drawText(text, r.left+px, r.top+py, paint);
}
}
public boolean onTouchEvent(MotionEvent event) {
scaleGestureDetector.onTouchEvent(event);
touched = true;
if (!panned){
left = event.getX() - rectHeight / 2;
top = event.getY() - rectWidth / 2;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
startPos.set(event.getX(), event.getY());
findWhatWasTouched();
invalidate();
break;
case MotionEvent.ACTION_POINTER_DOWN:
case MotionEvent.ACTION_MOVE:
if (freezeAction)
break;
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!scaleGestureDetector.isInProgress() && panned) {
xOffset += event.getX() - startPos.x;
yOffset += event.getY() - startPos.y;
} else
resetAllRectsAfterScrollOrZoom();
findWhatWasTouched();
invalidate();
startPos.set(event.getX(), event.getY());
break;
case MotionEvent.ACTION_POINTER_UP:
freezeAction = true;// When two fingers off of zoom, don't let the other finger jump everything around
break;
case MotionEvent.ACTION_UP:
if (!freezeAction){
findWhatWasTouched();
invalidate();
if (panned || zoomed)
resetAllRectsAfterScrollOrZoom();
}
liveRect = null;
panned = false;
freezeAction = false;
xOffset = 0;
yOffset =0;
break;
}
return true;
}
public void resetAllRectsAfterScrollOrZoom(){
float height, width;
for (RectF r: RectFs){
height = r.height();
width = r.width();
if (zoomed){
r.left += (xOffset * scaleFactor);
r.top += (yOffset * scaleFactor);
}else {
r.left += xOffset;
r.top += yOffset ;
}
r.right = r.left + width;
r.bottom = r.top + height;
}
}
public void findWhatWasTouched(){
boolean rectWasTouched = false;
for (RectF r: RectFs){ // Update positions due to a touch event.
if (r.contains(startPos.x, startPos.y)){
if (liveRect == null)
liveRect = r;
rectWasTouched = true;
}
}
if (!rectWasTouched)
panned = true;
if (!zoomed && !panned && liveRect != null){
float height = liveRect.height();
float width = liveRect.width();
liveRect.left = left;
liveRect.top = top;
liveRect.right = liveRect.left + width;
liveRect.bottom = liveRect.top + height; // We have a moving single rect - reset it's position here
}
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
scaleFactor *= detector.getScaleFactor();
zoomed = true;
// don't let the object get too small or too large.
scaleFactor = Math.max(0.1f, Math.min(scaleFactor, 5.0f));
return true;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector){
zoomed = false;
}
} // End ScaleListener class
} // End view class
最大的问题是，在缩放后，矩形的触摸会呈指数级地向下和向右移动...这让我想到重置所有矩形块中的缩放部分的数学计算可能有误。但是我无论如何都无法弄清楚。仍然不知道每次重置矩形坐标是否是正确的做法？