java swt 图像(图像数据)旋转

Question

我正在尝试做一个简单的程序，我可以在其中添加一些 png 到 Canvas 。其中一个选项是旋转选定的 png。我有旋转问题。当我使用 Transformation 时，它会旋转 Canvas 上的所有内容。我只创建了旋转 90' 或翻转的示例，但我想旋转任何角度。

我也曾尝试将 swt 图像转换为 bufferedimage，然后旋转，然后将 bufferedimage 转换为 swt 图像并绘制它，但速度非常慢，并且在透明度方面存在一些问题。

我将不胜感激 - 我想通过图像中心旋转。对于 drawig，我使用 GC 和 Canvas - new GC(canvas);

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编辑:我仍然无法按图像中心旋转:

gc.setAdvanced(true);
        if (!gc.getAdvanced()) {
            gc.drawText("Advanced graphics not supported", 30, 30, true);
            return;
        }

        Transform oldTransform = new Transform(gc.getDevice());  
        gc.getTransform(oldTransform);

        Transform transform = new Transform(GCController.getCanvas().getDisplay());
        transform.translate(width/2, height/2);
        transform.rotate(rotation);
        gc.setTransform(transform);
        gc.drawImage(image, x, y);

        gc.setTransform(oldTransform);

        transform.dispose();

Answer 1

你必须使用矩阵变换。看看this SWT 片段。作为引用，我以 15 度为例(接近尾声)。

import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class ImageTest {    
    public static void main(String[] args) {
        final Display display = new Display();

        final Image image = new Image(display,"next.png");


        final Rectangle rect = image.getBounds();
        Shell shell = new Shell(display);
        shell.setText("Matrix Tranformations");
        shell.setLayout(new FillLayout());
        final Canvas canvas = new Canvas(shell, SWT.DOUBLE_BUFFERED);
        canvas.addPaintListener(new PaintListener () {
            public void paintControl(PaintEvent e) {    
                GC gc = e.gc;
                gc.setAdvanced(true);
                if (!gc.getAdvanced()){
                    gc.drawText("Advanced graphics not supported", 30, 30, true);
                    return;
                }

                // Original image
                int x = 30, y = 30;
                gc.drawImage(image, x, y); 
                x += rect.width + 30;

                Transform transform = new Transform(display);

                // Note that the tranform is applied to the whole GC therefore
                // the coordinates need to be adjusted too.

                // Reflect around the y axis.
                transform.setElements(-1, 0, 0, 1, 0 ,0);
                gc.setTransform(transform);
                gc.drawImage(image, -1*x-rect.width, y);



                // Rotate by 45 degrees 
                float cos45 = (float)Math.cos(Math.PI/4);
                float sin45 = (float)Math.sin(Math.PI/4);
                transform.setElements(cos45, sin45, -sin45, cos45, 0, 0);
                gc.setTransform(transform);
                gc.drawImage(image, x , y);

                float cos15 = (float)Math.cos(Math.PI/12);
                float sin15 = (float)Math.sin(Math.PI/12);
                transform.setElements(cos15, sin15, -sin15, cos15, 0, 0);
                gc.setTransform(transform);
                gc.drawImage(image, x+rect.width/2 , y+rect.height/2);

                transform.dispose();
            }
        });

        shell.setSize(350, 550);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
        image.dispose();
        display.dispose();
    }
}

>>输出