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我正在製作一個繪圖應用程序，我所做的是從前一個視圖控制器中的相機膠捲中加載圖像，並將其發送到此處，然後加載它在mainImage中，然後應用程序在照片中做一些繪圖。現在，如果我選擇橡皮擦工具，我可以清除應用程序所畫的內容，但僅在第一次擦除時才起作用，因爲當我釋放第一次觸摸並嘗試再次擦除時，它什麼也不做。即使我選擇另一個按鈕來繪製其他線條，然後再次選擇橡皮擦，它也不會擦除。任何人都可以幫助我嗎？無法用石英2d繪製應用程序多次擦除畫出的線
@synthesize mainImage;
@synthesize tempDrawImage;
- (void)viewDidLoad
{
red = 255.0/255.0;
green = 0/255.0;
blue = 255.0/255.0;
brush = 10.0;
opacity = 1.0;
self.mainImage.image = [camViewController image]; //load photo from camera roll from previous view controller
[super viewDidLoad];
//draw line in the middle of the screen
[self drawMiddleRectangleBrushSize:20];
}
-(void)drawMiddleRectangleBrushSize:(float)brushSize{
UIGraphicsBeginImageContext(self.view.frame.size);
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), self.view.frame.size.width/2, 0);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), self.view.frame.size.width/2, self.view.frame.size.height);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brushSize);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
CGContextStrokePath(UIGraphicsGetCurrentContext());
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
[self.tempDrawImage setAlpha:opacity];
UIGraphicsEndImageContext();
}
- (IBAction)pencilPressed:(id)sender {
UIButton * PressedButton = (UIButton*)sender;
_eraserPress = NO;
switch(PressedButton.tag)
{
case 0:
red = 0.0/255.0;
green = 0.0/255.0;
blue = 0.0/255.0;
break;
case 1:
red = 105.0/255.0;
green = 105.0/255.0;
blue = 105.0/255.0;
break;
case 2:
red = 255.0/255.0;
green = 0.0/255.0;
blue = 0.0/255.0;
break;
case 3:
red = 0.0/255.0;
green = 0.0/255.0;
blue = 255.0/255.0;
break;
case 4:
red = 102.0/255.0;
green = 204.0/255.0;
blue = 0.0/255.0;
break;
case 5:
red = 102.0/255.0;
green = 255.0/255.0;
blue = 0.0/255.0;
break;
case 6:
red = 51.0/255.0;
green = 204.0/255.0;
blue = 255.0/255.0;
break;
case 7:
red = 160.0/255.0;
green = 82.0/255.0;
blue = 45.0/255.0;
break;
case 8:
red = 255.0/255.0;
green = 102.0/255.0;
blue = 0.0/255.0;
break;
case 9:
red = 255.0/255.0;
green = 255.0/255.0;
blue = 0.0/255.0;
break;
}
}
- (IBAction)eraserPressed:(id)sender {
red = 255.0/255.0;
green = 255.0/255.0;
blue = 255.0/255.0;
opacity = 1.0;
_eraserPress = YES;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = NO;
UITouch *touch = [touches anyObject];
lastPoint = [touch locationInView:self.view];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self.view];
if(_eraserPress == NO){
UIGraphicsBeginImageContext(self.view.frame.size);
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
CGContextStrokePath(UIGraphicsGetCurrentContext());
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
[self.tempDrawImage setAlpha:opacity];
UIGraphicsEndImageContext();
lastPoint = currentPoint;
}
if(_eraserPress == YES){
UIGraphicsBeginImageContext(self.view.frame.size);
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(),brush);
CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextSetShouldAntialias(UIGraphicsGetCurrentContext(), YES);
CGContextSetAllowsAntialiasing(UIGraphicsGetCurrentContext(), YES);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextSetFlatness(UIGraphicsGetCurrentContext(), 0.1f);
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
if(!mouseSwiped) {
UIGraphicsBeginImageContext(self.view.frame.size);
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, opacity);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextFlush(UIGraphicsGetCurrentContext());
self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
UIGraphicsBeginImageContext(self.mainImage.frame.size);
[self.mainImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
[self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:opacity];
self.mainImage.image = UIGraphicsGetImageFromCurrentImageContext();
self.tempDrawImage.image = nil;
UIGraphicsEndImageContext();
}