问题描述
在 SWT 中有没有办法将合成导出为始终具有相同大小/分辨率的图像?问题是我们有一个仪表板，当在具有不同显示尺寸/分辨率的屏幕上打开时，它看起来总是不同的.现在的问题是，我能否将仪表板导出为具有固定大小的图像，并且无论创建的屏幕尺寸/分辨率如何，它始终看起来相同?
Is there a way in SWT to export a composite to an image which always has the same size/resolution? The problem is that we have a Dashboard which looks always different when opening on screens with different display size/resolution. The question is now can I export the Dashboard to an image wich has a fixed size and always looks the same no matter on which screen size/resolution it has been created?
目前我们是这样做的，但如前所述，这取决于创建它的显示器:
For the time being we do it like that but as said it depends on the display it has been created on:
Image image = new Image(Display.getCurrent(), this.content.getBounds().width, this.content.getBounds().height);
ImageLoader loader = new ImageLoader();
FileOutputStream fileOutputStream = new FileOutputStream(file);
GC gc = new GC(image);
this.content.print(gc);
gc.dispose();
loader.data = new ImageData[] { image.getImageData() };
loader.save(fileOutputStream, imageFormat);
fileOutputStream.close();
例如，是否有某种方法可以创建具有特定分辨率的虚拟屏幕，但该屏幕实际上并未显示而仅用于导出仪表板?任何帮助或指示将不胜感激.
Is there for example some way to create a virtual screen with a certain resolution, which isn't actually displayed and only used for exporting the Dashboard?Any help or pointers would be appreciated.
推荐答案
在我的一个应用程序中，我使用 SWT 创建图形和图表.用户能够将这些导出为他们指定的大小和格式的图像.我的解决方案是获取图表合成的 GC 并将其重新绘制到屏幕外的新合成，然后导出新绘制的合成.
In one of my applications I was creating graphs and charts in SWT. The user was able to export these to an image of a size and format that they specified. My solution was to take the GC of the chart composite and redraw it to a new composite off screen, then export the newly drawn composite.
这是我完成的课程:
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.ImageLoader;
import org.eclipse.swt.widgets.Composite;
/**
* The class used for writing an {@link Composite} to an image file
*
* @author David L. Moffett
*
*/
public class CompositeImageWriter
{
/**
* Redraws the composite to the desired size off-screen and then writes that
* composite as an image to the desired location and in the desired format
*
* @param absolutePath
* the absolute path to the desired output file
* @param compositeToDraw
* the composite to be written to file as an image
* @param width
* the desired width in pixels that the composite should be redrawn
* to
* @param height
* the desired height in pixels that the composite should be redrawn
* to
* @param imageType
* an int representing the type of image that should be written
*/
public static void drawComposite(String absolutePath, Composite compositeToDraw, int width,
int height, int imageType)
{
Image image = new Image(compositeToDraw.getDisplay(), width, height);
GC gc = new GC(image);
int originalWidth = compositeToDraw.getBounds().width;
int originalHeight = compositeToDraw.getBounds().height;
compositeToDraw.setSize(width, height);
compositeToDraw.print(gc);
compositeToDraw.setSize(originalWidth, originalHeight);
ImageLoader loader = new ImageLoader();
loader.data = new ImageData[] { image.getImageData() };
loader.save(absolutePath, imageType);
image.dispose();
gc.dispose();
}
}
对于希望始终以特定尺寸导出的情况，只需将宽度和高度参数替换为适当的常量即可.
For your case of wanting to always export at a specific size, just replace the width and height arguments with appropriate constants.
编辑 1
我应该补充一点，int imageType 参数是相应的 SWT 修饰符(例如:SWT.IMAGE_PNG、SWT.IMAGE_JPEG、SWT.IMAGE_BMP 等...).
I should add that the int imageType argument is the corresponding SWT modifier (for example: SWT.IMAGE_PNG, SWT.IMAGE_JPEG, SWT.IMAGE_BMP, etc...).
编辑 2
我更新了静态引用，以便从 CompositeToDraw 动态获取显示.此外，这是我放在一起的一个示例，它使用 CompositeImageWriter 您可以用来调试您的问题:
I updated the static reference to dynamically get the display from the compositeToDraw. Further, here's an example I put together which uses the CompositeImageWriter which you may be able to use to debug your issue:
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Listener;
public class CompositeToWrite extends Composite
{
private int width, height;
private Label l;
public CompositeToWrite(Composite parent, int style)
{
super(parent, style);
this.setLayout(new GridLayout(1, true));
this.addListener(SWT.Resize, new Listener()
{
@Override
public void handleEvent(Event event)
{
updateText();
}
});
Button b = new Button(this, SWT.NONE);
b.setText("Export as image (500, 500)");
b.addListener(SWT.Selection, new Listener()
{
@Override
public void handleEvent(Event event)
{
CompositeImageWriter.drawComposite("./img/output.png", CompositeToWrite.this, 500, 500,
SWT.IMAGE_PNG);
}
});
l = new Label(this, SWT.CENTER);
GridData gd = new GridData(SWT.FILL, SWT.FILL, true, true);
gd.verticalAlignment = SWT.CENTER;
l.setLayoutData(gd);
updateText();
}
protected void updateText()
{
width = this.getBounds().width;
height = this.getBounds().height;
l.setText("My label is centered in composite (" + width + ", " + height + ")");
}
}
在这个例子中，我创建了一个简单的组合，一旦添加到 shell 中，它看起来像这样:
In the case of this example I create a simple composite that once added to a shell will look something like this:
当我单击按钮时，它会将合成大小调整为 500 x 500，并将调整后的合成大小写入文件.结果是这张图:
When I click the button it resizes the composite to 500 x 500 and writes the resized composite to a file. The result is this picture:
我应该注意到，当单击按钮时，我确实注意到复合闪烁，因此这可能不会完全发生在我最初建议的背景或屏幕外"中.
I should note that I did notice the composite flicker when the button is clicked, so this may not be happening completely in the background or "off screen" as I initially suggested.
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