很多天以来一直在与问题作斗争。希望我能在这里得到答案。我用过this链接以平滑我的手绘图。在这段代码中,我能够设置线宽和颜色,但是当我尝试使用 this 在其中包含撤消/重做功能时,我发现它非常困难。链接在撤消重做方面工作正常,但徒手绘制并不流畅。
经过一些研究和编码,我知道这是绘图的阻碍,我认为这阻止了撤消/重做。
在第一个链接中有一个文件“CachedLIView.h/m”,当我使用它并尝试在其中包含撤消/重做时,我发现在以下方法中:
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event // (2)
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p];
[self drawBitmap]; // (3)
[self setNeedsDisplay];
[path removeAllPoints]; //(4)
}
此方法正在调用drawBitMap:方法,该方法实际上在每次用户抬起手指并同时从“路径”中删除点时生成临时图像。
- (void)drawBitmap // (3)
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, 0.0);
[[UIColor blackColor] setStroke];
if (!incrementalImage) // first draw; paint background white by ...
{
UIBezierPath *rectpath = [UIBezierPath bezierPathWithRect:self.bounds]; // enclosing bitmap by a rectangle defined by another UIBezierPath object
[[UIColor greenColor] setFill];
[rectpath fill]; // filling it with white
}
[incrementalImage drawAtPoint:CGPointZero];
//[path stroke];
for (UIBezierPath *_path in pathArray)
[_path strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];
incrementalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
我将每个路径保存在数组中,以便我可以撤消/重做。 (从第二个链接中获取这个想法)。
下面是我修改后包含撤消/重做的该文件的完整代码:
#import "CachedLIView.h"
@implementation CachedLIView
{
UIBezierPath *path;
UIImage *incrementalImage; // (1)
}
- (id)initWithFrame:(CGRect)frame // (1)
{
if (self = [super initWithFrame:frame])
{
[self setMultipleTouchEnabled:NO]; // (2)
// [self setBackgroundColor:[UIColor whiteColor]];
// path = [[UIBezierPath alloc] init];
// [path setLineWidth:3];
pathArray=[[NSMutableArray alloc]init];
bufferArray=[[NSMutableArray alloc]init];
[self drawBitmap];
}
return self;
}
- (void)drawRect:(CGRect)rect
{
NSLog(@"in drawrect pathArray[count]: %d", pathArray.count);
[incrementalImage drawInRect:rect]; // (3)
//[[UIColor blackColor] setStroke];
//[path stroke];
for (UIBezierPath *_path in pathArray)
[_path strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
path = [[UIBezierPath alloc] init];
path.lineWidth = 3;
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path moveToPoint:p];
[pathArray addObject:path];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p];
[self setNeedsDisplay];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event // (2)
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
[path addLineToPoint:p];
[self drawBitmap]; // (3)
[self setNeedsDisplay];
[path removeAllPoints]; //(4)
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
[self touchesEnded:touches withEvent:event];
}
- (void)drawBitmap // (3)
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, 0.0);
[[UIColor blackColor] setStroke];
if (!incrementalImage) // first draw; paint background white by ...
{
UIBezierPath *rectpath = [UIBezierPath bezierPathWithRect:self.bounds]; // enclosing bitmap by a rectangle defined by another UIBezierPath object
[[UIColor greenColor] setFill];
[rectpath fill]; // filling it with white
}
[incrementalImage drawAtPoint:CGPointZero];
//[path stroke];
for (UIBezierPath *_path in pathArray)
[_path strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];
incrementalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
#pragma mark - undo/redo
-(void)undoButtonClicked
{
if([pathArray count]>0){
UIBezierPath *_path=[pathArray lastObject];
[bufferArray addObject:_path];
[pathArray removeLastObject];
[self drawBitmap];
[self setNeedsDisplay];
}
}
-(void)redoButtonClicked
{
if([bufferArray count]>0){
UIBezierPath *_path=[bufferArray lastObject];
[pathArray addObject:_path];
[bufferArray removeLastObject];
[self drawBitmap];
[self setNeedsDisplay];
}
}
@end
.h 文件是:
#import <UIKit/UIKit.h>
@interface CachedLIView : UIView
{
NSMutableArray *pathArray;
NSMutableArray *bufferArray;
UIBezierPath *myPath;
}
-(void)undoButtonClicked;
-(void)redoButtonClicked;
@end
请帮助我。我做错了什么。 pathArray 计数工作正常。但无法在屏幕上显示撤消/重做效果。
最佳答案
嘿,我无法获得您的完整代码,但我可以建议您我们如何实现这样的事情,
对于徒手图像绘制中的重做和撤消,您可以在触摸开始或触摸结束时捕获图像渲染
,并管理该堆栈渲染
。然后根据您的要求(重做/撤消)使用缓存中的渲染。所以步骤就像,
1) 当您触摸板时捕获渲染并保存。并在缓存中管理该序列。
- 因此,每次触摸开始时,您都必须捕获图像并按顺序保存。
2)当您按下撤消键时,获取最后的渲染并将其替换为您的板。
3) 对于重做,您可以检查是否有比当前替换的渲染更高的渲染可用。意味着您可以通过最后更新的渲染来启用和禁用该按钮。
4)完成保存图像后不要忘记清空缓存,这样您就可以管理下一次绘图的堆栈。
<小时/>- 如果您不明白这个想法,请告诉我。
关于iphone - 无法通过平滑的徒手绘图来包含撤消/重做,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13744160/