【IOS】仿 AppleTree 画板中的颜色选择器 （半成品）

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原文地址：http://blog.csdn.net/toss156/article/details/7542274】

花了两个晚上的时间，给大家带来一个颜色选择器。画图的部分用数组记录点，来绘制，感觉不是很流畅，希望有涂鸦类，或者小画板开发经验的童鞋透露点心得。

效果图:类似左边的这样的

// // ColorPicker.h // Draw // // Created by on 12-5-6. // Copyright (c) 2012年 __MyCompanyName__. All rights reserved. // #import <UIKit/UIKit.h> #import <QuartzCore/QuartzCore.h> #import "Canvas.h" @interface ColorPicker : UIView { CGContextRef contextref; UIImage * colorbar; UIImage * glass; UIColor * drawColor; CGPoint offsetPoint; unsigned char* data; size_t w; size_t h; Canvas *canvas; } @property (nonatomic,retain) UIImage *colorbar; @property (nonatomic,retain) UIImage *glass; @property (nonatomic,assign) CGContextRef contextref; @property (nonatomic,assign) CGPoint offsetPoint; @property (nonatomic,assign) UIColor * drawColor; @property (nonatomic,assign) Canvas *canvas; - (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage; - (UIColor*) getPixelColorAtLocation:(CGPoint)point; - (UIColor*) setGlassPoint:(CGPoint) point; - (void) getData; @end
// // ColorPicker.m // Draw // // Created by on 12-5-6. // Copyright (c) 2012年 __MyCompanyName__. All rights reserved. // #import "ColorPicker.h" @implementation ColorPicker @synthesize colorbar,glass,contextref,offsetPoint,drawColor,canvas; - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code self.colorbar = [UIImage imageNamed:@"colorbar.png"]; self.layer.cornerRadius = frame.size.width/2; self.layer.masksToBounds = YES; drawColor = [UIColor brownColor]; contextref = NULL; data = NULL; offsetPoint = CGPointMake(0, 0); } return self; } // Only override drawRect: if you perform custom drawing. // An empty implementation adversely affects performance during animation. - (void)drawRect:(CGRect)rect { // Drawing code CGContextRef context = UIGraphicsGetCurrentContext(); drawColor = [self getPixelColorAtLocation:CGPointMake(5, offsetPoint.y)]; [canvas setCurrentColor:drawColor]; CGContextSetFillColorWithColor(context,drawColor.CGColor); CGContextFillRect(context, rect); CGContextSaveGState(context); } -(UIColor *) setGlassPoint:(CGPoint) point { offsetPoint = CGPointMake(5, point.y-130); [self setNeedsDisplay]; return drawColor; } // Please refer to iOS Developer Library for more details regarding the following two methods - (UIColor*) getPixelColorAtLocation:(CGPoint)point { if (data == NULL) { [self getData]; } UIColor *tmpColor; if (data != NULL) { //offset locates the pixel in the data from x,y. //4 for 4 bytes of data per pixel, w is width of one row of data. int offset = 4*((w*round(point.y))); int alpha = data[offset]; int red = data[offset+1]; int green = data[offset+2]; int blue = data[offset+3]; tmpColor = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)]; } return tmpColor; } - (void) getData { CGImageRef inImage = self.colorbar.CGImage; // Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue if (contextref == NULL) { contextref = [self createARGBBitmapContextFromImage:inImage]; } if (contextref == NULL) { return; /* error */ } w = CGImageGetWidth(inImage); // problem! h = CGImageGetHeight(inImage); CGRect rect = {{0,0},{w,h}}; // Draw the image to the bitmap context. Once we draw, the memory // allocated for the context for rendering will then contain the // raw image data in the specified color space. CGContextDrawImage(contextref, rect, inImage); // Now we can get a pointer to the image data associated with the bitmap // context. data = CGBitmapContextGetData (contextref); } - (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage { CGContextRef context = NULL; CGColorSpaceRef colorSpace; void * bitmapData; int bitmapByteCount; int bitmapBytesPerRow; // Get image width, height. We'll use the entire image. size_t pixelsWide = CGImageGetWidth(inImage); size_t pixelsHigh = CGImageGetHeight(inImage); // Declare the number of bytes per row. Each pixel in the bitmap in this // example is represented by 4 bytes; 8 bits each of red, green, blue, and // alpha. bitmapBytesPerRow = (pixelsWide * 4); bitmapByteCount = (bitmapBytesPerRow * pixelsHigh); // Use the generic RGB color space. //colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB); //deprecated colorSpace = CGColorSpaceCreateDeviceRGB(); if (colorSpace == NULL) { fprintf(stderr, "Error allocating color space\n"); return NULL; } // Allocate memory for image data. This is the destination in memory // where any drawing to the bitmap context will be rendered. bitmapData = malloc( bitmapByteCount ); if (bitmapData == NULL) { fprintf (stderr, "Memory not allocated!"); CGColorSpaceRelease( colorSpace ); return NULL; } // Create the bitmap context. We want pre-multiplied ARGB, 8-bits // per component. Regardless of what the source image format is // (CMYK, Grayscale, and so on) it will be converted over to the format // specified here by CGBitmapContextCreate. context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, // bits per component bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst); if (context == NULL) { free (bitmapData); fprintf (stderr, "Context not created!"); } // Make sure and release colorspace before returning CGColorSpaceRelease( colorSpace ); return context; } -(void) dealloc { if(data) {free((data));} [colorbar release]; [glass release]; [super dealloc]; } @end

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