objective-c - 将未显示的 NSViewController 导出为 JPG

Question

我正在开发一个桌面应用程序，该应用程序从未显示的 NSViewController 生成图像。生成的 View 有 3 个 NSImageViews，一旦创建就会更改内容。

我设法将NSViewController的 View 导出为JPG文件，但它永远不会在提供给NSImageView的图像中呈现，它保留在 Nib 中设置的图像。另外，如果我没有将背景颜色设置为 View 的图层...我会得到一个空结果。

我在这里缺少什么？我想我需要更新 NSViewController 的 View ......但我该怎么做呢？我不想显示我的 NSViewController。

我的代码:

- (IBAction)doExport:(id)sender {
    ExportView *view = [[ExportView alloc] initWithNibName:@"ExportView" bundle:nil];
    [view.pic1 setImage:self.pic1.image];
    [view.pic2 setImage:self.pic2.image];
    [view.pic3 setImage:self.pic3.image];
    [view.icon setImage:self.icon.image];

    // Hardcoding for test
    [view.pic1 setImage:[NSImage imageNamed:@"iPhone 4-Inch Screenshot 1"]];
    [view.pic1 setNeedsLayout:YES];
    [view.pic1 setNeedsDisplay];
    [view.pic1 updateLayer];

    // Setup the image to render
    NSRect imgRect = view.view.frame;
    NSSize imgSize = imgRect.size;

    NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
                                                                    pixelsWide:imgSize.width
                                                                    pixelsHigh:imgSize.height
                                                                 bitsPerSample:8
                                                               samplesPerPixel:4
                                                                      hasAlpha:YES
                                                                      isPlanar:NO
                                                                colorSpaceName:NSDeviceRGBColorSpace
                                                                  bitmapFormat:NSAlphaFirstBitmapFormat
                                                                   bytesPerRow:0
                                                                  bitsPerPixel:0];

    NSGraphicsContext *g = [NSGraphicsContext graphicsContextWithBitmapImageRep:rep];
    [NSGraphicsContext saveGraphicsState];
    [NSGraphicsContext setCurrentContext:g];

    // Set view background color
    CALayer *viewLayer = [CALayer layer];
    [viewLayer setBackgroundColor:[NSColor clearColor].CGColor];
    [view.view setWantsLayer:YES];
    [view.view setLayer:viewLayer];

    // Render
    CGContextRef zCgContextRef = (CGContextRef) [g graphicsPort];
    [[view.view layer] renderInContext:zCgContextRef];

    // Render pic as well, for test
    [view.pic1.layer renderInContext:zCgContextRef];

    // Get the Data for the image
    NSData *exportedData = [rep representationUsingType:NSJPEGFileType properties:nil];

    // Start the savepanel
    NSSavePanel *savepanel = [NSSavePanel savePanel];
    savepanel.title = @"Save chart";

    [savepanel setAllowedFileTypes:[NSArray arrayWithObject:@"jpg"]];

    [savepanel beginSheetModalForWindow:self.window completionHandler:^(NSInteger result)
     {
         if (NSFileHandlingPanelOKButton == result)
         {
             NSURL* fileURL = [savepanel URL];

             if ([fileURL.pathExtension isEqualToString:@""])
                 fileURL = [fileURL URLByAppendingPathExtension:@"jpg"];

             [exportedData writeToURL:fileURL atomically:YES];
         }
     }];
}

Answer 1

我用一种非常丑陋的方式解决了这个问题。基本上我所做的就是将 View 添加到我的 contentView 中，并立即将 setHidden 设置为 YES 。这将初始化 View 。现在我更改 Nib View 的内容。当需要将数据渲染到 NSData 时，我将 setHidden 更改为 NO，生成 NSData，然后删除看法。

最终结果(没有漂亮的代码:( ):

- (IBAction)doExport:(id)sender {
    ExportView *view = [[ExportView alloc] initWithNibName:@"ExportView" bundle:nil];
    [view.view setHidden:YES];
    [self.window.contentView addSubview:view.view];

    [view.pic1 setImage:self.pic1.image];
    [view.pic2 setImage:self.pic2.image];
    [view.pic3 setImage:self.pic3.image];
    [view.icon setImage:self.icon.image];

    // Setup the image to render
    NSRect imgRect = view.view.frame;
    NSSize imgSize = imgRect.size;

    NSBitmapImageRep *rep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL
                                                                    pixelsWide:imgSize.width
                                                                    pixelsHigh:imgSize.height
                                                                 bitsPerSample:8
                                                               samplesPerPixel:4
                                                                      hasAlpha:YES
                                                                      isPlanar:NO
                                                                colorSpaceName:NSDeviceRGBColorSpace
                                                                  bitmapFormat:NSAlphaFirstBitmapFormat
                                                                   bytesPerRow:0
                                                                  bitsPerPixel:0];

    NSGraphicsContext *g = [NSGraphicsContext graphicsContextWithBitmapImageRep:rep];
    [NSGraphicsContext saveGraphicsState];
    [NSGraphicsContext setCurrentContext:g];

    // Set view background color
    CALayer *viewLayer = [CALayer layer];
    [viewLayer setBackgroundColor:[NSColor clearColor].CGColor];
    [view.view setWantsLayer:YES];
    [view.view setLayer:viewLayer];

    [view.view setHidden:NO];

    // Render
    CGContextRef zCgContextRef = (CGContextRef) [g graphicsPort];
    [[view.view layer] renderInContext:zCgContextRef];

    [view.view removeFromSuperview];

    // Get the Data for the image
    NSData *exportedData = [rep representationUsingType:NSJPEGFileType properties:nil];

    // Start the savepanel
    NSSavePanel *savepanel = [NSSavePanel savePanel];
    savepanel.title = @"Save chart";

    [savepanel setAllowedFileTypes:[NSArray arrayWithObject:@"jpg"]];
    [savepanel setNameFieldStringValue:@"Test"];

    [savepanel beginSheetModalForWindow:self.window completionHandler:^(NSInteger result)
     {
         if (NSFileHandlingPanelOKButton == result)
         {
             NSURL* fileURL = [savepanel URL];

             if ([fileURL.pathExtension isEqualToString:@""])
                 fileURL = [fileURL URLByAppendingPathExtension:@"jpg"];

             [exportedData writeToURL:fileURL atomically:YES];
         }
     }];
}