我显然遗漏了一些大而简单的东西，但我无法找到它。我有一个带有背景图像的表面视图，几个移动/可移动的精灵，并且可以缩放和平移图像。一切正常......除非在翻译画布时用第二个指针触摸。
如果画布是0,0，没问题。如果画布已翻译，则第一个指针没有问题。但是，如果第二次手指接触，它会捕捉到0,0。抬起第二根手指，然后快速向后翻转。
看起来像一个简单的修复 - 如果第二个指针，保持翻译值。但这就是问题 - 日志显示它 保持tx值 - 它从不在任何地方显示0,0。
我尝试过使用if (activePointer != INVALID_POINTER_ID)方法＆amp;它做同样的事情。当日志显示翻译值没有改变时，我只能弄清楚是什么告诉画布跳转到0,0。
以下是我的许多头痛尝试中的一个示例：
boolean doTouchEvent(MotionEvent ev) {
synchronized (gvSurfaceHolder) {
mScaleDetector.onTouchEvent(ev);
float x = ev.getX(0);
float y = ev.getY(0);
// get pointer index from the event object
int pointerIndex = ev.getActionIndex();
// get pointer ID
int pointerId = ev.getPointerId(pointerIndex);
switch (ev.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
contact = false;
// mLastTouch handles the finger position for moving the sprites
// translate handles where to move the whole screen when NOT touching sprites
mLastTouchX = x / mScaleFactor;
mLastTouchY = y / mScaleFactor;
//We assign the current X and Y coordinate of the finger to startX and startY minus the previously
//translated amount for each coordinates This works even when we are translating the first
//time because the initial values for these two variables is zero.
startX = x - previousTranslateX;
startY = y - previousTranslateY;
detectPCTouch();
if (contact){
mLastTouchX = startX / mScaleFactor;
mLastTouchY = startY / mScaleFactor;
}testVarDump("Down", pointerIndex, pointerId);
break;
case MotionEvent.ACTION_POINTER_DOWN:
stopTranslate = true;
testVarDump("ACTION Pointer DOWN", pointerIndex, pointerId);
break;
case MotionEvent.ACTION_MOVE:
x = ev.getX(0);
y = ev.getY(0);
//testVarDump("ACTION Move", pointerIndex, pointerId);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()){
if (!contact){
translateX = x - startX;
translateY = y - startY;
mLastTouchX = x / mScaleFactor;
mLastTouchY = y / mScaleFactor;
}else{
translateX = previousTranslateX;
translateY = previousTranslateY;
mLastTouchX = (x - previousTranslateX) / mScaleFactor;
mLastTouchY = (y - previousTranslateY) / mScaleFactor;
}
}
break;
case MotionEvent.ACTION_POINTER_UP:
contact = false;
stopTranslate = true;
testVarDump("ACTION Pointer UP", pointerIndex, pointerId);
break;
case MotionEvent.ACTION_UP:
// All fingers went up, so let's save the value of translateX and translateY into
// previousTranslateX and previousTranslate
if (!contact){
previousTranslateX = translateX;
previousTranslateY = translateY;
}else{
translateY = previousTranslateY;
translateX = previousTranslateX;
}
contact = false;
stopTranslate = false;testVarDump("ACTION Up", pointerIndex, pointerId);
break;
}
}
return true;
}
运行块：
@Override
public void run() {
while (running) {
Canvas c = null;
try {
c = gvSurfaceHolder.lockCanvas(null);
synchronized (gvSurfaceHolder) {
c.save();
c.scale(mScaleFactor, mScaleFactor);
//If translateX times -1 is lesser than zero, let's set it to zero. This takes care of the left bound
if((translateX * -1) < 0)
translateX = 0;
//This is where we take care of the right bound. We compare translateX times -1 to (scaleFactor - 1) * displayWidth.
//If translateX is greater than that value, then we know that we've gone over the bound. So we set the value of
//translateX to (1 - scaleFactor) times the display width. Notice that the terms are interchanged; it's the same
//as doing -1 * (scaleFactor - 1) * displayWidth
else if((translateX * -1) > (mScaleFactor - 1) * screenW)
translateX = (1 - mScaleFactor) * screenW;
if(translateY * -1 < 0)
translateY = 0;
//We do the exact same thing for the bottom bound, except in this case we use the height of the display
else if((translateY * -1) > (mScaleFactor - 1) * screenH)
translateY = (1 - mScaleFactor) * screenH;
if (!mScaleDetector.isInProgress())
c.translate(translateX / mScaleFactor, translateY / mScaleFactor);
// Here I'd expect translateX to be 0, but always logs as correctly
// translated, even when the background snaps to 0,0 with second pointer touch
if (stopTranslate)
testVarDump("DRAW", 0 ,0);
updateBadGuys();
detectCollision();
draw(c);
c.restore();
}
} finally {
if (c != null)
gvSurfaceHolder.unlockCanvasAndPost(c);
}
}
我在这里有点疯狂 - 任何想法当第二根手指上升或下降时是什么迫使翻译？请帮忙 - 我错过了什么？