当我为UITabBar制作图标时,它会对图像应用渐变。我需要知道如何防止它出现这种渐变。
答案 0 :(得分:27)
Apple在iOS 5中添加了标签栏自定义,现在这种东西是微不足道的。在此之前它是一个巨大的黑客,不推荐。
以下是完全自定义标签栏的方法:
// custom icons
UITabBarItem *item = [[UITabBarItem alloc] init];
item.title = @"foo";
// setting custom images prevents the OS from applying a tint color
[item setFinishedSelectedImage:[UIImage imageNamed:@"tab1_active.png"] withFinishedUnselectedImage:[UIImage imageNamed:@"tab1_image_deselected.png"]];
tab1ViewController.tabBarItem = item;
// tab bar
// set background image - will be used instead of glossy black
tabBarController.tabBar.backgroundImage = [UIImage imageNamed:@"tab_bar_bg.png"];
// optionally set the tint color - setting this ti nil will result in the standard, blue tint color. tint color is ignored when custom icons are set as above.
tabBarController.tabBar.selectedImageTintColor = nil;
// remove the highlight around the selected tab - or provide an alternate highlight image. If you don't do this the iOS default is to draw a highlighted box beneath the selected tab icon.
tabBarController.tabBar.selectionIndicatorImage = [[UIImage alloc] init];
答案 1 :(得分:18)
这是非常困难的,因为UITabBar
无法访问其选定/未选定的图像。它可以通过私有API来实现:
@interface UITabBar (ColorExtensions)
- (void)recolorItemsWithColor:(UIColor *)color shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur;
@end
@interface UITabBarItem (Private)
@property(retain, nonatomic) UIImage *selectedImage;
- (void)_updateView;
@end
@implementation UITabBar (ColorExtensions)
- (void)recolorItemsWithColor:(UIColor *)color shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur
{
CGColorRef cgColor = [color CGColor];
CGColorRef cgShadowColor = [shadowColor CGColor];
for (UITabBarItem *item in [self items])
if ([item respondsToSelector:@selector(selectedImage)] &&
[item respondsToSelector:@selector(setSelectedImage:)] &&
[item respondsToSelector:@selector(_updateView)])
{
CGRect contextRect;
contextRect.origin.x = 0.0f;
contextRect.origin.y = 0.0f;
contextRect.size = [[item selectedImage] size];
// Retrieve source image and begin image context
UIImage *itemImage = [item image];
CGSize itemImageSize = [itemImage size];
CGPoint itemImagePosition;
itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2);
itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2);
UIGraphicsBeginImageContext(contextRect.size);
CGContextRef c = UIGraphicsGetCurrentContext();
// Setup shadow
CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor);
// Setup transparency layer and clip to mask
CGContextBeginTransparencyLayer(c, NULL);
CGContextScaleCTM(c, 1.0, -1.0);
CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y, itemImageSize.width, -itemImageSize.height), [itemImage CGImage]);
// Fill and end the transparency layer
CGContextSetFillColorWithColor(c, cgColor);
contextRect.size.height = -contextRect.size.height;
CGContextFillRect(c, contextRect);
CGContextEndTransparencyLayer(c);
// Set selected image and end context
[item setSelectedImage:UIGraphicsGetImageFromCurrentImageContext()];
UIGraphicsEndImageContext();
// Update the view
[item _updateView];
}
}
@end
甚至可以创造一些很酷的效果:
(来源:booleanmagic.com)
Apple很可能拒绝执行此操作的申请。如果在未来的操作系统更新中删除了私有API,则-[UITabBar recolorItemsWithColor:shadowColor:shadowOffset:shadowBlur:]
将不会执行任何操作而不会崩溃。
答案 2 :(得分:4)
添加渐变非常简单,添加以下代码行:
CGFloat components[8] = {0.0,0.4,1.0,0.2,0.0,0.6,1.0,1.0};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, NULL, 2);
CGContextDrawLinearGradient(cxt, colorGradient,CGPointZero,CGPointMake(0,contextRect.size.height),0);
这将使您非常接近Apple在标签栏上所做的事情,但不完全一样。要实现这一目标,只需在组件中添加两个点/颜色,而不是NULL
中的CGGradientCreateWithColorComponents
,请使用{0,0.5,0.6,1.0}
之类的内容。实际上,您只需要一种背景颜色和三个alpha点(颜色部分全部为1,因为您只需要在保留单个颜色配置文件的同时进行着色)。
如果不清楚,我会发布我的代码...干杯。
答案 3 :(得分:3)
已经差不多一年了,但这里是代码。将此作为类别添加到UIImage或转换为类范围。请记住,您传递的图像(自身)必须是仅alpha图像(蒙版是基于图像的可见部分创建的)。
- (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor
shadeAlpha1:(CGFloat)alpha1
shadeAlpha2:(CGFloat)alpha2
shadeAlpha3:(CGFloat)alpha3
shadowColor:(UIColor *)shadowColor
shadowOffset:(CGSize)shadowOffset
shadowBlur:(CGFloat)shadowBlur {
UIImage *image = self;
CGColorRef cgColor = [bgColor CGColor];
CGColorRef cgShadowColor = [shadowColor CGColor];
CGFloat components[16] = {1,1,1,alpha1,1,1,1,alpha1,1,1,1,alpha2,1,1,1,alpha3};
CGFloat locations[4] = {0,0.5,0.6,1};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, (size_t)4);
CGRect contextRect;
contextRect.origin.x = 0.0f;
contextRect.origin.y = 0.0f;
contextRect.size = [image size];
//contextRect.size = CGSizeMake([image size].width+5,[image size].height+5);
// Retrieve source image and begin image context
UIImage *itemImage = image;
CGSize itemImageSize = [itemImage size];
CGPoint itemImagePosition;
itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2);
itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2);
UIGraphicsBeginImageContext(contextRect.size);
CGContextRef c = UIGraphicsGetCurrentContext();
// Setup shadow
CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor);
// Setup transparency layer and clip to mask
CGContextBeginTransparencyLayer(c, NULL);
CGContextScaleCTM(c, 1.0, -1.0);
CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y, itemImageSize.width, -itemImageSize.height), [itemImage CGImage]);
// Fill and end the transparency layer
CGContextSetFillColorWithColor(c, cgColor);
contextRect.size.height = -contextRect.size.height;
CGContextFillRect(c, contextRect);
CGContextDrawLinearGradient(c, colorGradient,CGPointZero,CGPointMake(contextRect.size.width*1.0/4.0,contextRect.size.height),0);
CGContextEndTransparencyLayer(c);
//CGPointMake(contextRect.size.width*3.0/4.0, 0)
// Set selected image and end context
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGColorSpaceRelease(colorSpace);
CGGradientRelease(colorGradient);
return resultImage;
}
例如,以下内容将产生与本机tabbar非常类似的效果:
UIImage *niceImage = [[UIImage imageNamed:@"image_name"] imageWithBackgroundColor:[UIColor colorWithRed:41.0/255.0 green:147.0/255.0 blue:239.0/255.0 alpha:1.0]
shadeAlpha1:0.6
shadeAlpha2:0.0
shadeAlpha3:0.4
shadowColor:[UIColor blackColor]
shadowOffset:CGSizeMake(0.0f, -1.0f)
shadowBlur:3.0];
答案 4 :(得分:3)
使用iDev Recipes网站上的自定义实施标签栏可以解决此问题。
http://idevrecipes.com/2011/01/04/how-does-the-twitter-iphone-app-implement-a-custom-tab-bar
答案 5 :(得分:1)
使用以下图像(假设,tabBar有5个标签,如下所示)
使用“TabBar应用程序”模板创建一个新项目&放置以下代码。
AppDel.h文件的内容。
#import <UIKit/UIKit.h>
@interface cTabBarAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) IBOutlet UITabBarController *tabBarController;
@property (nonatomic, retain) IBOutlet UIImageView *imgV;
@end
AppDel.m文件的内容。
#import "cTabBarAppDelegate.h"
@implementation cTabBarAppDelegate
@synthesize window=_window;
@synthesize tabBarController=_tabBarController;
@synthesize imgV = _imgV;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.tabBarController.delegate=self;
self.imgV.frame=CGRectMake(0, 425, 320, 55);
[self.tabBarController.view addSubview:self.imgV];
self.tabBarController.selectedIndex=0;
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];
return YES;
}
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController{
NSUInteger index=[[tabBarController viewControllers] indexOfObject:viewController];
switch (index) {
case 0:
self.imgV.image=[UIImage imageNamed:@"tBar1.png"];
break;
case 1:
self.imgV.image=[UIImage imageNamed:@"tBar2.png"];
break;
case 2:
self.imgV.image=[UIImage imageNamed:@"tBar3.png"];
break;
case 3:
self.imgV.image=[UIImage imageNamed:@"tBar4.png"];
break;
case 4:
self.imgV.image=[UIImage imageNamed:@"tBar5.png"];
break;
default:
break;
}
return YES;
}
答案 6 :(得分:1)
我问了一个关于如何为按钮的“offstate”着色的问题。有人给了我一个解决方案,也有删除渐变的奖金。这是问题和答案:
问:iphone - tabbar set imagetintcolor (offstate)
答:看看UITabBarItem文档的“管理已完成和选定的图像”任务的部分。