級別： ★★☆☆☆
標(biāo)簽：「iPhone app 圖標(biāo)」「圖標(biāo)生成」「啟動(dòng)圖生成」「QiAppIconGenerator」
作者： Xs·H
審校： QiShare團(tuán)隊(duì)

一個(gè)完整的app都需要多種尺寸的圖標(biāo)和啟動(dòng)圖涤妒。一般情況，設(shè)計(jì)師根據(jù)開發(fā)者提供的一套規(guī)則赚哗，設(shè)計(jì)出圖標(biāo)和啟動(dòng)圖供開發(fā)人員使用她紫。但最近我利用業(yè)余時(shí)間做了個(gè)app，不希望耽誤設(shè)計(jì)師較多時(shí)間屿储，就只要了最大尺寸的圖標(biāo)和啟動(dòng)圖各一個(gè)贿讹。本想著找一下現(xiàn)成的工具，批量生成需要的的圖片够掠，但最后沒有找到民褂，只好使用Photoshop切出了不同尺寸的圖片。這期間祖屏，設(shè)計(jì)師還換過一次圖標(biāo)和啟動(dòng)圖助赞，我就重復(fù)了切圖工作，這花費(fèi)了我大量的時(shí)間袁勺。于是事后雹食，作者開發(fā)了一個(gè)mac app——圖標(biāo)&啟動(dòng)圖生成器（簡稱生成器）以提高工作效率。作者用兩篇文章分別介紹生成器的使用和實(shí)現(xiàn)細(xì)節(jié)期丰。

接上篇文章群叶，本篇文章介紹生成器的實(shí)現(xiàn)細(xì)節(jié)。

生成器的工程非常簡單钝荡，可以概括為一個(gè)界面街立、一個(gè)資源文件和一個(gè)ViewController。結(jié)構(gòu)如下圖埠通。

一赎离、 界面

生成器app只有一個(gè)界面，因?yàn)榻缑鎻?fù)雜度較小端辱，作者選用了Storyboard+Constraints的方式進(jìn)行開發(fā)梁剔。下圖顯示了界面中的控件和約束情況虽画。

其中各控件對應(yīng)的類如下所示。

二荣病、 資源文件

app所支持的平臺規(guī)則數(shù)據(jù)從資源文件QiConfiguration.plist中獲取码撰。QiConfiguration.plist相當(dāng)于一個(gè)字典，每個(gè)平臺對應(yīng)著字典的一對key和value;
value是一個(gè)數(shù)組个盆，存儲(chǔ)著該平臺所需要的一組尺寸規(guī)格數(shù)據(jù)（item）脖岛；
item是尺寸規(guī)格數(shù)據(jù)的最小單元，內(nèi)部標(biāo)記了該尺寸規(guī)格的圖片的用途颊亮、名稱和尺寸柴梆。

QiConfiguration.plist的具體結(jié)構(gòu)如下圖所示。

三编兄、 ViewController

工程使用默認(rèn)的ViewController管理界面轩性、資源數(shù)據(jù)和邏輯。
首先狠鸳，界面控件元素在ViewController中對應(yīng)下圖中的5個(gè)實(shí)例揣苏。

其中，imageView件舵、platformBox和pathField不需要響應(yīng)方法卸察。并且，platfromBox和_pathField的默認(rèn)/記憶數(shù)據(jù)由NSUserDefaults管理铅祸。

static NSString * const selectedPlatformKey = @"selectedPlatform";
static NSString * const exportedPathKey = @"exportedPath";

- (void)viewDidLoad {
    
    [super viewDidLoad];
    
    NSString *selectedPlatform = [[NSUserDefaults standardUserDefaults] objectForKey:selectedPlatformKey];
    [_platformBox selectItemWithObjectValue:selectedPlatform];
    
    NSString *lastExportedPath = [[NSUserDefaults standardUserDefaults] objectForKey:exportedPathKey];
    _pathField.stringValue = lastExportedPath ?: NSHomeDirectory();
}

這里忽略這三個(gè)控件坑质，重點(diǎn)介紹pathButton和exportButton的響應(yīng)方法中的代碼邏輯。

1. - pathButtonClicked:

pathButton的響應(yīng)方法負(fù)責(zé)打開文件目錄临梗，并回傳選擇的路徑給pathField涡扼，以顯示出來。
代碼如下：

- (IBAction)pathButtonClicked:(NSButton *)sender {
    
    NSOpenPanel *openPanel = [NSOpenPanel openPanel];
    openPanel.canChooseDirectories = YES;
    openPanel.canChooseFiles = NO;
    openPanel.title = @"選擇導(dǎo)出目錄";
    [openPanel beginSheetModalForWindow:self.view.window completionHandler:^(NSModalResponse result) {
        if (result == NSModalResponseOK) {
            self.pathField.stringValue = openPanel.URL.path;
        }
    }];
}

2. - exportButtonClicked:

exportButton的響應(yīng)方法負(fù)責(zé)根據(jù)imageView中的源圖片盟庞、platform中選擇的平臺規(guī)則和pathField中顯示的導(dǎo)出路徑生成圖片并打開圖片所在的文件夾吃沪。
代碼如下：

- (IBAction)exportButtonClicked:(NSButton *)sender {
    
    NSImage *image = _imageView.image;
    NSString *platform = _platformBox.selectedCell.title;
    NSString *exportPath = _pathField.stringValue;
    
    if (!image || !platform || !exportPath) {
        NSAlert *alert = [[NSAlert alloc] init];
        alert.messageText = @"請先選擇源圖片、平臺和導(dǎo)出路徑";
        alert.alertStyle = NSAlertStyleWarning;
        [alert addButtonWithTitle:@"確認(rèn)"];
        [alert beginSheetModalForWindow:self.view.window completionHandler:^(NSModalResponse returnCode) {}];
    }
    else {
        [[NSUserDefaults standardUserDefaults] setObject:platform forKey:selectedPlatformKey];
        [[NSUserDefaults standardUserDefaults] synchronize];
        [[NSUserDefaults standardUserDefaults] setObject:exportPath forKey:exportedPathKey];
        [[NSUserDefaults standardUserDefaults] synchronize];
        
        [self generateImagesForPlatform:platform fromOriginalImage:image];
    }
}

- (void)generateImagesForPlatform:(NSString *)platform fromOriginalImage:(NSImage *)originalImage {
    
    NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"QiConfiguration" ofType:@"plist"];
    NSDictionary *configuration = [NSDictionary dictionaryWithContentsOfFile:plistPath];
    NSArray<NSDictionary *> *items = configuration[platform];
    
    NSString *directoryPath = [[_pathField.stringValue stringByAppendingPathComponent:platform] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    [[NSFileManager defaultManager] createDirectoryAtPath:directoryPath withIntermediateDirectories:YES attributes:nil error:nil];
    
    if ([platform containsString:@"AppIcons"]) {
        [self generateAppIconsWithConfigurations:items fromOriginalImage:originalImage toDirectoryPath:directoryPath];
    }
    else if ([platform containsString:@"LaunchImages"]) {
        [self generateLaunchImagesWithConfigurations:items fromOriginalImage:originalImage toDirectoryPath:directoryPath];
    }
}

- (void)generateAppIconsWithConfigurations:(NSArray<NSDictionary *> *)configurations fromOriginalImage:(NSImage *)originalImage toDirectoryPath:(NSString *)directoryPath {
    
    for (NSDictionary *configuration in configurations) {
        NSImage *appIcon = [self generateAppIconWithImage:originalImage forSize:NSSizeFromString(configuration[@"size"])];
        NSString *filePath = [NSString stringWithFormat:@"%@/%@.png", directoryPath, configuration[@"name"]];
        [self exportImage:appIcon toPath:filePath];
    }
    [[NSWorkspace sharedWorkspace] openURL:[NSURL fileURLWithPath:directoryPath isDirectory:YES]];
}

- (void)generateLaunchImagesWithConfigurations:(NSArray<NSDictionary *> *)configurations fromOriginalImage:(NSImage *)originalImage toDirectoryPath:(NSString *)directoryPath {
    
    for (NSDictionary *configuration in configurations) {
        NSImage *launchImage = [self generateLaunchImageWithImage:originalImage forSize: NSSizeFromString(configuration[@"size"])];
        
        NSString *filePath = [NSString stringWithFormat:@"%@/%@.png", directoryPath, configuration[@"name"]];
        [self exportImage:launchImage toPath:filePath];
    }
    [[NSWorkspace sharedWorkspace] openURL:[NSURL fileURLWithPath:directoryPath isDirectory:YES]];
}

- (NSImage *)generateAppIconWithImage:(NSImage *)fromImage forSize:(CGSize)toSize  {
    
    NSRect toFrame = NSMakeRect(.0, .0, toSize.width, toSize.height);
    toFrame = [[NSScreen mainScreen] convertRectFromBacking:toFrame];
    
    NSImageRep *imageRep = [fromImage bestRepresentationForRect:toFrame context:nil hints:nil];
    NSImage *toImage = [[NSImage alloc] initWithSize:toFrame.size];
    
    [toImage lockFocus];
    [imageRep drawInRect:toFrame];
    [toImage unlockFocus];
    
    return toImage;
}

- (NSImage *)generateLaunchImageWithImage:(NSImage *)fromImage forSize:(CGSize)toSize {
    
    // 計(jì)算目標(biāo)小圖去貼合源大圖所需要放大的比例
    CGFloat wFactor = fromImage.size.width / toSize.width;
    CGFloat hFactor = fromImage.size.height / toSize.height;
    CGFloat toFactor = fminf(wFactor, hFactor);
    
    // 根據(jù)所需放大的比例什猖，計(jì)算與目標(biāo)小圖同比例的源大圖的剪切Rect
    CGFloat scaledWidth = toSize.width * toFactor;
    CGFloat scaledHeight = toSize.height * toFactor;
    CGFloat scaledOriginX = (fromImage.size.width - scaledWidth) / 2;
    CGFloat scaledOriginY = (fromImage.size.height - scaledHeight) / 2;
    NSRect fromRect = NSMakeRect(scaledOriginX, scaledOriginY, scaledWidth, scaledHeight);
    
    // 生成即將繪制的目標(biāo)圖和目標(biāo)Rect
    NSRect toRect = NSMakeRect(.0, .0, toSize.width, toSize.height);
    toRect = [[NSScreen mainScreen] convertRectFromBacking:toRect];
    NSImage *toImage = [[NSImage alloc] initWithSize:toRect.size];
    
    // 繪制
    [toImage lockFocus];
    [fromImage drawInRect:toRect fromRect:fromRect operation:NSCompositeCopy fraction:1.0];
    [toImage unlockFocus];
    
    return toImage;
}

- (void)exportImage:(NSImage *)image toPath:(NSString *)path {
    
    NSData *imageData = image.TIFFRepresentation;
    NSData *exportData = [[NSBitmapImageRep imageRepWithData:imageData] representationUsingType:NSPNGFileType properties:@{}];
    
    [exportData writeToFile:path atomically:YES];
}

上述是工程的所有代碼票彪，代碼較多。建議有需要的同學(xué)移步至工程源碼閱讀不狮。

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