撤消/重做以在iOS中绘图
我正在绘制一个绘图应用程序，我想做Undo / Redo，为此我在结束NSMutableArray的触摸上保存CGPath，但我不明白如何在点击撤消按钮时渲染CGPath
EDIT1：
当我使用BezierPaths时，我首先决定采用一种简单的方法来调整此路径，而不使用CGPath，
EDIT2：由于我的Undo发生在片段中（我，部分而不是整个路径被删除），我决定创建一个数组数组，所以我已经做了相应的更改，现在我将在CGlayer中绘图，服用CGPath
所以这里“parentUndoArray”是数组数组。
所以我这样做了
我有一个名为DrawingPath的类，它将执行绘图
//DrawingPath.h
@interface DrawingPath : NSObject
@property (strong, nonatomic) NSString *pathWidth;
@property (strong,nonatomic) UIColor *pathColor;
@property (strong,nonatomic) UIBezierPath *path;
- (void)draw;
@end
//DrawingPath.m
#import "DrawingPath.h"
@implementation DrawingPath
@synthesize pathWidth = _pathWidth;
@synthesize pathColor = _pathColor;
@synthesize path = _path;
- (id)init {
if (!(self = [super init] ))
return nil;
_path = [[UIBezierPath alloc] init];
_path.lineCapStyle=kCGLineCapRound;
_path.lineJoinStyle=kCGLineJoinRound;
[_path setLineWidth:2.0f];
return self;
}
- (void)draw
{
[self.pathColor setStroke];
[self.path stroke];
}
所以现在在我的DrawingView中，我这样做
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
ctr = 0;
bufIdx = 0;
UITouch *touch = [touches anyObject];
pts[0] = [touch locationInView:self];
isFirstTouchPoint = YES;
[m_undoArray removeAllObjects];//On every touches began clear undoArray
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint p = [touch locationInView:self];
ctr++;
pts[ctr] = p;
if (ctr == 4)
{
pts[3] = midPoint(pts[2], pts[4]);
for ( int i = 0; i < 4; i++)
{
pointsBuffer[bufIdx + i] = pts[i];
}
bufIdx += 4;
dispatch_async(drawingQueue, ^{
self.currentPath = [[DrawingPath alloc] init];
[self.currentPath setPathColor:self.lineColor];
if (bufIdx == 0) return;
LineSegment ls[4];
for ( int i = 0; i < bufIdx; i += 4)
{
if (isFirstTouchPoint) // ................. (3)
{
ls[0] = (LineSegment){pointsBuffer[0], pointsBuffer[0]};
[self.currentPath.path moveToPoint:ls[0].firstPoint];
// [offsetPath addLineToPoint:ls[0].firstPoint];
isFirstTouchPoint = NO;
}
else
{
ls[0] = lastSegmentOfPrev;
}
float frac1 = self.lineWidth/clamp(len_sq(pointsBuffer[i], pointsBuffer[i+1]), LOWER, UPPER); // ................. (4)
float frac2 = self.lineWidth/clamp(len_sq(pointsBuffer[i+1], pointsBuffer[i+2]), LOWER, UPPER);
float frac3 = self.lineWidth/clamp(len_sq(pointsBuffer[i+2], pointsBuffer[i+3]), LOWER, UPPER);
ls[1] = [self lineSegmentPerpendicularTo:(LineSegment){pointsBuffer[i], pointsBuffer[i+1]} ofRelativeLength:frac1]; // ................. (5)
ls[2] = [self lineSegmentPerpendicularTo:(LineSegment){pointsBuffer[i+1], pointsBuffer[i+2]} ofRelativeLength:frac2];
ls[3] = [self lineSegmentPerpendicularTo:(LineSegment){pointsBuffer[i+2], pointsBuffer[i+3]} ofRelativeLength:frac3];
[self.currentPath.path moveToPoint:ls[0].firstPoint]; // ................. (6)
[self.currentPath.path addCurveToPoint:ls[3].firstPoint controlPoint1:ls[1].firstPoint controlPoint2:ls[2].firstPoint];
[self.currentPath.path addLineToPoint:ls[3].secondPoint];
[self.currentPath.path addCurveToPoint:ls[0].secondPoint controlPoint1:ls[2].secondPoint controlPoint2:ls[1].secondPoint];
[self.currentPath.path closePath];
lastSegmentOfPrev = ls[3]; // ................. (7)
}
[m_undoArray addObject:self.currentPath];
EDIT:2
CGPathRef cgPath = self.currentPath.path.CGPath;
mutablePath = CGPathCreateMutableCopy(cgPath);
dispatch_async(dispatch_get_main_queue(), ^{
bufIdx = 0;
[self setNeedsDisplay];
});
});
pts[0] = pts[3];
pts[1] = pts[4];
ctr = 1;
}
}
}
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[parentUndoArray addObject:m_undoArray];
}
我的drawRect方法在
之下编辑：现在我的DrawRect有两个案例
- (void)drawRect:(CGRect)rect
{
switch (m_drawStep)
{
case DRAW:
{
CGContextRef context = UIGraphicsGetCurrentContext();//Get a reference to current context(The context to draw)
CGContextRef layerContext = CGLayerGetContext(self.currentDrawingLayer);
CGContextBeginPath(layerContext);
CGContextAddPath(layerContext, mutablePath);
CGContextSetStrokeColorWithColor(layerContext, self.lineColor.CGColor);
CGContextSetFillColorWithColor(layerContext, self.lineColor.CGColor);
CGContextSetBlendMode(layerContext,kCGBlendModeNormal);
CGContextDrawPath(layerContext, kCGPathFillStroke);
// CGPathRelease(mutablePath);
CGContextDrawLayerInRect(context,rectSize, self.newDrawingLayer);
CGContextDrawLayerInRect(context, self.bounds, self.permanentDrawingLayer);
CGContextDrawLayerInRect(context, self.bounds, self.currentDrawingLayer );
}
break;
case UNDO:
{
for(int i = 0; i<[m_parentUndoArray count];i++)
{
NSMutableArray *undoArray = [m_parentUndoArray objectAtIndex:i];
for(int i =0; i<[undoArray count];i++)
{
DrawingPath *drawPath = [undoArray objectAtIndex:i];
[drawPath draw];
}
}
}
break;
[super drawRect:rect];
}
EDIT2：现在我面临的问题是，即使我绘制小路径或大路径，数组数组中的数据也是相同的。但事实上，小路径应该包含较小的drawingPath对象，而大路径应该在undoArray中包含更多的drawingPath对象，最后将其添加到名为“ParentUndoArray
的数组的数组中”以下是截屏，
1.第一个屏幕在不拉动手指的情况下一次性拍摄画线
2，执行撤消操作一次后，只删除该行的一段
4 个答案:
答案 0 :(得分：2)
我找到了一个解决方案，我们需要创建一个DrawingPaths数组的数组：
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
// Do the above code, then
[m_undoArray addObject:self.currentPath];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
[m_parentUndoArray addObject:[NSArray arrayWithArray:m_undoArray]];
}
然后在DrawRect中描述路径。
答案 1 :(得分：1)
如果你的drawRect方法可以绘制数组中的任何CGPath，你需要做的只是在删除最后添加的CGPath之后通过调用setNeedsDisplay在你的Undo方法中再次触发绘图
答案 2 :(得分：1)
我认为你制作的路径对象比你想要的多。我建议转到你在触摸中分配bezierPath的地方移动并替换
self.currentPath = [[DrawingPath alloc] init];
用
if(!self.currentPath){
self.currentPath = [[DrawingPath alloc] init];
}
答案 3 :(得分：0)
嗯，你应该这样做，因为它很容易
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.backgroundColor = [UIColor clearColor];
myPath = [[UIBezierPath alloc] init];
myPath.lineCapStyle = kCGLineCapRound;
myPath.miterLimit = 0;
bSize=5;
myPath.lineWidth = bSize;
brushPattern = [UIColor whiteColor];
// Arrays for saving undo-redo steps in arrays
pathArray = [[NSMutableArray alloc] init];
bufferArray = [[NSMutableArray alloc] init];
}
return self;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
[brushPattern setStroke];
for (id path in pathArray){
if ([path isKindOfClass:[UIBezierPath class]]) {
UIBezierPath *_path=(UIBezierPath *)path;
[_path strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];
}
}
}
#pragma mark - Touch Methods
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *mytouch = [[touches allObjects] objectAtIndex:0];
myPath = [[UIBezierPath alloc] init];
myPath.lineWidth = bSize;
[myPath moveToPoint:[mytouch locationInView:self]];
[pathArray addObject:myPath];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
[myPath addLineToPoint:[[touches anyObject] locationInView:self]];
[self setNeedsDisplay];
}
#pragma mark - Undo Method
-(void)undoButtonClicked
{
if([pathArray count]>0)
{
if ([[pathArray lastObject] isKindOfClass:[SPUserResizableView class]])
{
[[pathArray lastObject] removeFromSuperview];
}
UIBezierPath *_path = [pathArray lastObject];
[bufferArray addObject:_path];
[pathArray removeLastObject];
[self setNeedsDisplay];
}
}
-(void)setBrushSize: (CGFloat)brushSize
{
bSize=brushSize;
}
-(void)redoButtonClicked
{
if([bufferArray count]>0){
UIBezierPath *_path = [bufferArray lastObject];
[pathArray addObject:_path];
[bufferArray removeLastObject];
[self setNeedsDisplay];
}
}
-(void)undoAllButtonClicked
{
[pathArray removeAllObjects];
[self setNeedsDisplay];
}
希望它会有所帮助。
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