objective-c - 如何获取 QLPreviewView 内容并写入图像

Question

我只是写了一个小演示。它的所有功能都是使用 QLPreviewView 来快速查看页面文件。 当应用程序运行时，您可以滚动查看Pages文件内容，当您单击“保存到PNG”按钮时，应用程序会将当前显示的内容保存到PNG图像文件中。您可以在 save 方法中获取实现。我刚刚尝试了该方法的两种实现，但都不起作用。 我刚刚得到一个填充了窗口背景颜色的空白图像。这里有一些建议吗？谢谢。

代码和应用程​​序屏幕截图可以在这里找到 http://dr.ibuick.com/updU

#import <Cocoa/Cocoa.h>
#import <Quartz/Quartz.h>
#import <QuickLook/QuickLook.h>
#import "IBAppDelegate.h"

@interface IBAppDelegate (QLPreviewItem) <QLPreviewItem>

@end

@implementation IBAppDelegate (QLPreviewItem)

    - (NSURL *)previewItemURL
    {
        return self.resolvedFileURL;
    }

    - (NSString *)previewItemTitle
    {
        return [self.originalURL absoluteString];
    }

@end

@implementation IBAppDelegate

    - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
    {
        _resolvedFileURL = [NSURL fileURLWithPath:@"/Users/buick/Desktop/1.pages"];
        _originalURL = [NSURL fileURLWithPath:@"/Users/buick/Desktop/1.pages"];
        _previewView = [[QLPreviewView alloc] initWithFrame:NSMakeRect(0, 50, 480, 360) 
                        style:QLPreviewViewStyleNormal];
        [_previewView setPreviewItem:self];
        [self.window.contentView addSubview:_previewView];
    }

    - (IBAction)save:(id)sender {

        // Method 1

        [_previewView lockFocus];
        NSBitmapImageRep* rep = [_previewView     
            bitmapImageRepForCachingDisplayInRect:_previewView.bounds];
        [_previewView cacheDisplayInRect:_previewView.bounds toBitmapImageRep:rep];
        [_previewView unlockFocus];
        [[rep representationUsingType:NSPNGFileType properties:nil] 
            writeToFile:@"/Users/buick/Desktop/1.png" atomically:YES];

        // Method 2
        [_previewView lockFocus];

        NSBitmapImageRep *bits;
        bits = [[NSBitmapImageRep alloc]
            initWithFocusedViewRect:[_previewView visibleRect]];
        [_previewView unlockFocus];
        NSData *imageData;
        NSDictionary *imageProps = [NSDictionary dictionaryWithObject:[NSNumber             
            numberWithFloat:0.9] forKey:NSImageCompressionFactor];
        imageData = [bits representationUsingType:NSJPEGFileType     
            properties:imageProps];
        [imageData writeToFile:@"/Users/buick/Desktop/1.png" atomically:YES];
    }
@end

Answer 1

好的，我想我明白了。尝试在初始化时将 QLPreviewView 类型设置为 QLPreviewViewStyleCompact。

pv = [[QLPreviewView alloc] initWithFrame:pv.bounds
                                    style:QLPreviewViewStyleCompact];

然后使用这个类别

NSImage+QuickLook from Matt Gemmel...

github

NSImage *image = [NSImage imageWithPreviewOfFileAtPath:[[self.files objectAtIndex:i] path] ofSize:NSMakeSize(1200, 1920) asIcon:NO];