這個問題是從後面的另一個SO問題的後續:zooming using pinch but not using transform methods。我的縮放工作非常接近完美,但它仍然會讓繪製的圖像像我一直在說的那樣「跳來跳去」。代碼的最重要的部分如下:縮放從縮放位置上的CGContext上繪製的圖像
當觀察到夾送事件調用此方法:
[代碼段1]
- (IBAction)handlePinchGesture:(UIGestureRecognizer *)sender {
float previousZoomLevel = zoomLevel;
UIPinchGestureRecognizer *pinch = (UIPinchGestureRecognizer *)sender;
float zoomIncreaseFactor = [self getZoomFactor:[pinch scale]]; //= 13 or 7 or 10
float estimatedDelta = (previousZoomLevel * zoomIncreaseFactor)/150;
if ([pinch scale] > previousScale) {
zoomLevel += estimatedDelta;
}
if ([pinch scale] < previousScale) {
zoomLevel -= estimatedDelta;
}
previousScale = [pinch scale];
if (zoomLevel < MIN_ZOOM_LEVEL) {
zoomLevel = MIN_ZOOM_LEVEL;
}
if (zoomLevel > MAX_ZOOM_LEVEL) {
zoomLevel = MAX_ZOOM_LEVEL;
}
CGPoint loc = [pinch locationInView:self];
NSLog(@"loc: {%.1f,%.1f}, lastPinchLoc: {%.1f,%.1f}", loc.x,loc.y,lastPinchLocation.x,lastPinchLocation.y);
//uncomment the below part to always zoom from the first zoom location.
//if (lastPinchLocation.x != 0 && lastPinchLocation.y != 0) {
//loc.x += lastPinchLocation.x - loc.x;
//loc.y += lastPinchLocation.y - loc.y;
//}
//NSLog(@"newLastPinchLocation: {%.1f,%.1f}", loc.x,loc.y);
lastPinchLocation = loc;
hasBeenMoved = YES;
if (zoomLevel != previousZoomLevel) {
[self setNeedsDisplay];
}
}
上面的NSLog給出以下打印時我捏整個屏幕:
2012-10-16 10:15:19.357 App[2609:907] loc: {147.0,232.0}, lastPinchLoc: {0.0,0.0}
2012-10-16 10:15:19.391 App[2609:907] loc: {147.0,231.0}, lastPinchLoc: {147.0,232.0}
2012-10-16 10:15:19.436 App[2609:907] loc: {148.0,232.0}, lastPinchLoc: {147.0,231.0}
2012-10-16 10:15:19.457 App[2609:907] loc: {148.0,232.0}, lastPinchLoc: {148.0,232.0}
2012-10-16 10:15:19.474 App[2609:907] loc: {148.0,233.0}, lastPinchLoc: {148.0,232.0}
2012-10-16 10:15:19.507 App[2609:907] loc: {147.0,233.0}, lastPinchLoc: {148.0,233.0}
2012-10-16 10:15:19.573 App[2609:907] loc: {103.0,355.0}, lastPinchLoc: {147.0,233.0}
2012-10-16 10:15:20.324 App[2609:907] loc: {585.0,710.0}, lastPinchLoc: {103.0,355.0}
2012-10-16 10:15:20.340 App[2609:907] loc: {584.0,709.0}, lastPinchLoc: {585.0,710.0}
2012-10-16 10:15:20.356 App[2609:907] loc: {584.0,710.0}, lastPinchLoc: {584.0,709.0}
2012-10-16 10:15:20.374 App[2609:907] loc: {584.0,710.0}, lastPinchLoc: {584.0,710.0}
2012-10-16 10:15:20.407 App[2609:907] loc: {583.0,710.0}, lastPinchLoc: {584.0,710.0}
2012-10-16 10:15:20.456 App[2609:907] loc: {512.0,811.0}, lastPinchLoc: {583.0,710.0}
2012-10-16 10:15:21.056 App[2609:907] loc: {645.0,163.0}, lastPinchLoc: {512.0,811.0}
2012-10-16 10:15:21.090 App[2609:907] loc: {647.0,164.0}, lastPinchLoc: {645.0,163.0}
2012-10-16 10:15:21.107 App[2609:907] loc: {647.0,165.0}, lastPinchLoc: {647.0,164.0}
2012-10-16 10:15:21.156 App[2609:907] loc: {602.0,249.0}, lastPinchLoc: {647.0,165.0}
2012-10-16 10:15:21.839 App[2609:907] loc: {153.0,702.0}, lastPinchLoc: {602.0,249.0}
2012-10-16 10:15:21.856 App[2609:907] loc: {157.0,703.0}, lastPinchLoc: {153.0,702.0}
2012-10-16 10:15:21.874 App[2609:907] loc: {159.0,704.0}, lastPinchLoc: {157.0,703.0}
2012-10-16 10:15:21.890 App[2609:907] loc: {160.0,704.0}, lastPinchLoc: {159.0,704.0}
2012-10-16 10:15:21.906 App[2609:907] loc: {123.0,796.0}, lastPinchLoc: {160.0,704.0}
2012-10-16 10:15:21.923 App[2609:907] loc: {125.0,794.0}, lastPinchLoc: {123.0,796.0}
2012-10-16 10:15:22.706 App[2609:907] loc: {368.0,303.0}, lastPinchLoc: {125.0,794.0}
2012-10-16 10:15:22.723 App[2609:907] loc: {369.0,307.0}, lastPinchLoc: {368.0,303.0}
2012-10-16 10:15:22.725 App[2609:907] loc: {369.0,307.0}, lastPinchLoc: {369.0,307.0}
2012-10-16 10:15:22.739 App[2609:907] loc: {371.0,312.0}, lastPinchLoc: {369.0,307.0}
2012-10-16 10:15:22.756 App[2609:907] loc: {374.0,312.0}, lastPinchLoc: {371.0,312.0}
2012-10-16 10:15:22.773 App[2609:907] loc: {338.0,392.0}, lastPinchLoc: {374.0,312.0}
剛上CGContext上的X和Y繪製項目之前投入這個方法,我畫上了返回的位置的項目。類變量'zoomTouchLocation'與上面代碼片段中的'lastPinchLocation'具有相同的值。
[代碼段2]
- (CGPoint)handleCoordinatesX:(float)x y:(float)y {
x -= zoomTouchLocation.x;
y -= zoomTouchLocation.y;
x = x * zoomLevel;
y = y * zoomLevel;
x += zoomTouchLocation.x;
y += zoomTouchLocation.y;
return CGPointMake(x, y);
}
如果我捏在大致相同的位置,每次都如預期它會工作,但是當我捏遍屏幕上的圖像周圍跳躍像瘋了似的。
現在基本上我的問題是,如果任何人都可以幫助我解決這個「跳來跳去」的問題,並讓圖像從我放大的位置縮放而不跳來跳去。如果您需要更多信息,請在下面的評論中提問。
(我知道這是相當正常的跳躍我的代碼出現,因爲它是,我只是無法找到方法,從這樣做,阻止它)
你試圖過濾輸入值?即不允許跳躍?另一個問題是 - 從300件事情到700件事情時 - 你做了什麼?是否可以在另一個視圖上觸發(即不同的座標系)? – Magnus
不,我現在沒有過濾輸入(我將在下週嘗試),而且我沒有在不同的座標系上工作。問題是,實際捏手勢是在一個完全不同的地方比以前。那是什麼時候發生跳躍 – Manuel
@ hims056 - 嗯,你是對的,那真是太傻了。猜猜我會先喝一杯咖啡。 – Manuel