Samples > 画像を任意に拡大することが可能なCanvasクラス

 

画像を任意に拡大することが可能なCanvasクラス

イメージの拡大・縮小が変えられるCanvasクラスのサンプルです。使い方は、

ScaleableImageCanvas c = 
    new ScaleableImageCanvas(shell, SWT.BORDER, "sample.jpg");

という感じで通常のCanvasクラスのコンストラクタ引き数にロードする画像のファイル名を与えます。画像のスケーリングを行うには、下のようにchangeScaleメソッドを使ってスケールを指定します。この場合は、オリジナルの画像の1.1倍の画像が表示されることになります。

c.changeScale(1.1);

ScaleableImageCanvasTestを実行すると以下のようなアプリケーションが起動し、スケールバーでイメージのサイズを変更することが可能です。

スクリーンショット

ソースコード(ScaleableImageCanvasTest.java)

import org.eclipse.swt.widgets.*;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.*;

public class ScaleableImageCanvasTest {

        private ScaleableImageCanvas c;
        private double scale = 1.0;
        
        public static void main(String[] args) {
                new ScaleableImageCanvasTest();
        }
        public ScaleableImageCanvasTest() {
                Display display = new Display();
                Shell shell = new Shell(display);
                shell.setText("ScaleableImageCanvasTest");
                shell.setLayout(new GridLayout(1, false));
                GridData gd;

                final ScaleableImageCanvas c 
                   = new ScaleableImageCanvas(shell, SWT.BORDER, "sky.jpg");
                gd = new GridData();
                gd.widthHint = 300;
                gd.heightHint = 200;
                c.setLayoutData(gd);
        
                final Scale scale = new Scale(shell, SWT.HORIZONTAL);
                scale.setMinimum(50);
                scale.setMaximum(200);
                scale.setSelection(100);
                scale.setToolTipText("100%");
                scale.addSelectionListener(new SelectionAdapter() {
                        public void widgetSelected(SelectionEvent e) {
                                int value = scale.getSelection();
                                c.changeScale((double) value * 0.01);
                                scale.setToolTipText("" + value + "%");
                        }
                });
                gd = new GridData(GridData.FILL_HORIZONTAL);
                scale.setLayoutData(gd);

                shell.pack();
                shell.open();
                while (!shell.isDisposed()) {
                        if (!display.readAndDispatch()) {
                                display.sleep();
                        }
                }
                display.dispose();
        }
}

ソースコード (ScaleableImageCanvas.java)

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.*;

public class ScaleableImageCanvas extends Canvas {

        private Image image;
        private int width;
        private int height;
        private Display display;
        private double scale = 1.0;
        private int ix = 0;
        private int iy = 0;
        private Shell shell;
        

        public ScaleableImageCanvas(Composite parent, int style, String filename) {
                super(parent, style | SWT.H_SCROLL | SWT.V_SCROLL | SWT.NO_REDRAW_RESIZE);
                display = parent.getDisplay();

                image = new Image(display, filename);
                width = image.getImageData().width;
                height = image.getImageData().height;

                //Canvasにスクロールバーを設定する
                ScrollBar horizontalBar = getHorizontalBar();
                horizontalBar.setVisible(true);
                horizontalBar.setMinimum(0);
                horizontalBar.setEnabled(false);
                horizontalBar.addSelectionListener(new SelectionAdapter() {
                        public void widgetSelected(SelectionEvent event) {
                                scrollHorizontally((ScrollBar)event.widget);
                        }
                });
                
                ScrollBar verticalBar = getVerticalBar();
                verticalBar.setVisible(true);
                verticalBar.setMinimum(0);
                verticalBar.setEnabled(false);
                verticalBar.addSelectionListener(new SelectionAdapter() {
                        public void widgetSelected(SelectionEvent event) {
                                scrollVertically((ScrollBar)event.widget);
                        }
                });             
                
                shell = parent.getShell();
                shell.addControlListener(new ControlAdapter(){
                        public void controlResized(ControlEvent e) {
                                resizeShell(e);
                        }

                });

                addPaintListener(new PaintListener() {
                        public void paintControl(PaintEvent e) {
                                int scaledWidth = (int) ((double) width * scale);
                                int scaledHeight = (int) ((double) height * scale);
                                e.gc.drawImage(
                                        image,
                                        0,
                                        0,
                                        width,
                                        height,
                                        ix,
                                        iy,
                                        scaledWidth,
                                        scaledHeight);

                        }
                });
        }

        public void changeScale(double d) {
                scale = d;
                resizeScrollBars();     
                redraw();
        }

        protected void resizeShell(ControlEvent e) {
                if (image == null || shell.isDisposed()){
                        return;
                }
                resizeScrollBars();
        }

        private void resizeScrollBars() {               
                ScrollBar horizontal = this.getHorizontalBar();
                ScrollBar vertical = this.getVerticalBar();
                Rectangle canvasBounds = this.getClientArea();
                int scaledWidth = (int)Math.round(width * scale);
                if (scaledWidth > canvasBounds.width) {
                        // イメージがCanvasよりも大きくなった場合
                        horizontal.setEnabled(true);
                        horizontal.setMaximum(scaledWidth);
                        horizontal.setThumb(canvasBounds.width);
                        horizontal.setPageIncrement(canvasBounds.width);
                } else {
                        // Canvasがイメージよりも大きい場合
                        horizontal.setEnabled(false);
                        if (ix != 0) {
                                ix = 0;
                                this.redraw();
                        }
                }
                int scaledHeight = (int)Math.round(height * scale);
                if (scaledHeight > canvasBounds.height) {
                        // イメージがCanvasよりも大きくなった場合
                        vertical.setEnabled(true);
                        vertical.setMaximum(scaledHeight);
                        vertical.setThumb(canvasBounds.height);
                        vertical.setPageIncrement(canvasBounds.height);
                } else {
                        // Canvasがイメージよりも大きい場合
                        vertical.setEnabled(false);
                        if (iy != 0) {
                                // Make sure the image is completely visible.
                                iy = 0;
                                this.redraw();
                        }
                }               
        }

        protected void scrollVertically(ScrollBar bar) {
                Rectangle canvasBounds = this.getClientArea();
                                
                int scaledWidth = (int)Math.round(width * scale);
                int scaledHeight = (int)Math.round(height * scale);
                if (scaledHeight > canvasBounds.height) {
                        int y = -bar.getSelection();
                        if (y + scaledHeight < canvasBounds.height) {
                                y = canvasBounds.height - scaledHeight;
                        }
                        this.scroll(ix, y, ix, iy, scaledWidth, scaledHeight, false);
                        iy = y;
                }               
        }

        protected void scrollHorizontally(ScrollBar bar) {
                Rectangle canvasBounds = this.getClientArea();  
                int scaledWidth = (int)Math.round(width * scale);
                int scaledHeight = (int)Math.round(height * scale);
                if (scaledWidth > canvasBounds.width) {
                        int x = -bar.getSelection();
                        if (x + scaledWidth < canvasBounds.width) {
                                x = canvasBounds.width - scaledWidth;
                        }
                        this.scroll(x, iy, ix, iy, scaledWidth, scaledHeight, false);
                        ix = x;
                }               
        }

        public void dispose() {
                image.dispose();
                super.dispose();
        }

}
 

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