ImageIconをラベルサイズに合わせて自動的にスケーリングします
私のJFrameでは、次のコードを使用してパネルに画像を表示しています。
ImageIcon img= new ImageIcon("res.png");
jLabel.setIcon(img);
ラベル内の画像を「自動サイズ調整」したいと思います。実際、画像サイズが数ピクセルしかない場合もあります。
ラベルのサイズを設定してから、ラベル内の画像のサイズを自動調整する方法はありますか？
これは難しい質問です。 JLabelを使用して画像を表示しているという事実を強調します。これは物事を行うための標準的な方法ですが、JLabelはテキスト、アイコン、テキストの配置を備えた複雑な小さな獣ですそしてポジショニング。
余分な機能がすべて必要ない場合は、スケーリングされた画像をペイントできるカスタムコンポーネントを作成するだけです...
次の質問は、どのように画像を拡大縮小したいですか？画像のアスペクト比を維持しますか？画像を使用可能なスペースに「合わせる」か「塗りつぶす」か。
@Davidは正しい。可能な場合は、Image#getScaledInstanceこれは最速ではありませんが、より重要なことは、一般に、最高品質も提供されないことです。
フィットvsフィル
次の例はかなり単純です（そして、私のコードライブラリから重い借用しているため、おそらく少し複雑です;））。バックグラウンドスケーリングスレッドから使用できますが、元の画像の潜在的なサイズに基づいて判断します。
public class ResizableImage {
public static void main(String[] args) {
new ResizableImage();
}
public ResizableImage() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
try {
BufferedImage image = ImageIO.read(new File("/path/to/your/image"));
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new ScalablePane(image));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (Exception exp) {
exp.printStackTrace();
}
}
});
}
public class ScalablePane extends JPanel {
private Image master;
private boolean toFit;
private Image scaled;
public ScalablePane(Image master) {
this(master, true);
}
public ScalablePane(Image master, boolean toFit) {
this.master = master;
setToFit(toFit);
}
@Override
public Dimension getPreferredSize() {
return master == null ? super.getPreferredSize() : new Dimension(master.getWidth(this), master.getHeight(this));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Image toDraw = null;
if (scaled != null) {
toDraw = scaled;
} else if (master != null) {
toDraw = master;
}
if (toDraw != null) {
int x = (getWidth() - toDraw.getWidth(this)) / 2;
int y = (getHeight() - toDraw.getHeight(this)) / 2;
g.drawImage(toDraw, x, y, this);
}
}
@Override
public void invalidate() {
generateScaledInstance();
super.invalidate();
}
public boolean isToFit() {
return toFit;
}
public void setToFit(boolean value) {
if (value != toFit) {
toFit = value;
invalidate();
}
}
protected void generateScaledInstance() {
scaled = null;
if (isToFit()) {
scaled = getScaledInstanceToFit(master, getSize());
} else {
scaled = getScaledInstanceToFill(master, getSize());
}
}
protected BufferedImage toBufferedImage(Image master) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
BufferedImage image = createCompatibleImage(masterSize);
Graphics2D g2d = image.createGraphics();
g2d.drawImage(master, 0, 0, this);
g2d.dispose();
return image;
}
public Image getScaledInstanceToFit(Image master, Dimension size) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
return getScaledInstance(
toBufferedImage(master),
getScaleFactorToFit(masterSize, size),
RenderingHints.VALUE_INTERPOLATION_BILINEAR,
true);
}
public Image getScaledInstanceToFill(Image master, Dimension size) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
return getScaledInstance(
toBufferedImage(master),
getScaleFactorToFill(masterSize, size),
RenderingHints.VALUE_INTERPOLATION_BILINEAR,
true);
}
public Dimension getSizeToFit(Dimension original, Dimension toFit) {
double factor = getScaleFactorToFit(original, toFit);
Dimension size = new Dimension(original);
size.width *= factor;
size.height *= factor;
return size;
}
public Dimension getSizeToFill(Dimension original, Dimension toFit) {
double factor = getScaleFactorToFill(original, toFit);
Dimension size = new Dimension(original);
size.width *= factor;
size.height *= factor;
return size;
}
public double getScaleFactor(int iMasterSize, int iTargetSize) {
return (double) iTargetSize / (double) iMasterSize;
}
public double getScaleFactorToFit(Dimension original, Dimension toFit) {
double dScale = 1d;
if (original != null && toFit != null) {
double dScaleWidth = getScaleFactor(original.width, toFit.width);
double dScaleHeight = getScaleFactor(original.height, toFit.height);
dScale = Math.min(dScaleHeight, dScaleWidth);
}
return dScale;
}
public double getScaleFactorToFill(Dimension masterSize, Dimension targetSize) {
double dScaleWidth = getScaleFactor(masterSize.width, targetSize.width);
double dScaleHeight = getScaleFactor(masterSize.height, targetSize.height);
return Math.max(dScaleHeight, dScaleWidth);
}
public BufferedImage createCompatibleImage(Dimension size) {
return createCompatibleImage(size.width, size.height);
}
public BufferedImage createCompatibleImage(int width, int height) {
GraphicsConfiguration gc = getGraphicsConfiguration();
if (gc == null) {
gc = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
}
BufferedImage image = gc.createCompatibleImage(width, height, Transparency.TRANSLUCENT);
image.coerceData(true);
return image;
}
protected BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor, Object hint, boolean bHighQuality) {
BufferedImage imgScale = img;
int iImageWidth = (int) Math.round(img.getWidth() * dScaleFactor);
int iImageHeight = (int) Math.round(img.getHeight() * dScaleFactor);
if (dScaleFactor <= 1.0d) {
imgScale = getScaledDownInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
} else {
imgScale = getScaledUpInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
}
return imgScale;
}
protected BufferedImage getScaledDownInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = (img.getTransparency() == Transparency.OPAQUE)
? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
if (targetHeight > 0 || targetWidth > 0) {
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(Math.max(w, 1), Math.max(h, 1), type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
} else {
ret = new BufferedImage(1, 1, type);
}
return ret;
}
protected BufferedImage getScaledUpInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w < targetWidth) {
w *= 2;
if (w > targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h < targetHeight) {
h *= 2;
if (h > targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
tmp = null;
} while (w != targetWidth || h != targetHeight);
return ret;
}
}
}
ラベルのサイズを設定する方法はありますか
JLabelのgetPreferredSize()をオーバーライドし、必要なDimensionsを返しますが、JLabelはコンテンツに合わせてサイズを調整するため、画像のサイズを変更する必要があります。 JLabelに追加します。
ラベル内の画像のサイズを自動調整するには？
必要な幅と高さに応じて画像のサイズを変更する必要があります（JLabelに追加するだけで、JLabelは画像に合わせてサイズ変更されます）。
私はImage.getScaledInstance(..)をお勧めしません
- Image.getScaledInstance（）の危険 主に概説されている問題は次のとおりです。
Image.getScaledInstance()は、完成したスケーリングされた画像を返しません。後で画像ピクセルが使用されるときに、スケーリング作業の多くが残ります。
以下は、getScaledInstanceによって作成された問題を回避するために私が使用しているカスタムメソッドです。
public static BufferedImage resize(BufferedImage image, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, width, height, null);
g2d.dispose();
return bi;
}
次の方法で、希望するサイズの画像を作成します。
BufferedImage image=ImageIO.read(..);
BufferedImage resizedImage=resize(image,100,100);//resize the image to 100x100
paintComponentのJLabelメソッドをオーバーライドし、imageと同じ幅と高さを持つJLabelを描画することでも可能です。また、親containerのサイズを変更するときに画像のサイズを変更する場合は、親コンテナにWindowListenerを適用し、毎回repaintにJlabelインスタンスを適用できます親コンテナのサイズが変更されます。デモは次のとおりです。
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import javax.swing.SwingUtilities;
import Java.awt.Graphics;
import Java.awt.event.WindowAdapter;
import Java.awt.event.WindowEvent;
public class LabelDemo extends JFrame
{
ImageIcon imageIcon;
MyJLabel jLabel ;
public LabelDemo ()
{
super("JLabel Demo");
}
public void createAndShowGUI()
{
imageIcon = new ImageIcon("Apple.png");
jLabel = new MyJLabel(imageIcon);
getContentPane().add(jLabel);
addWindowListener( new WindowAdapter()
{
public void windowResized(WindowEvent evt)
{
jLabel.repaint();
}
});
setSize(300,100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
jLabel.repaint();
}
public static void main(String st[])
{
SwingUtilities.invokeLater( new Runnable()
{
@Override
public void run()
{
LabelDemo demo = new LabelDemo();
demo.createAndShowGUI();
}
});
}
}
class MyJLabel extends JLabel
{
ImageIcon imageIcon;
public MyJLabel(ImageIcon icon)
{
super();
this.imageIcon = icon;
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(imageIcon.getImage(),0,0,getWidth(),getHeight(),this);
}
}
ストレッチアイコン を使用できます。
画像は、ラベルで使用できるスペースを埋めるために自動的にサイズ変更されます。画像を比例的に拡大縮小するか、領域全体に拡大縮小するかを制御できます。
StretchIconを使用すると、アイコンをサポートするコンポーネントの自動サイズ変更の恩恵を受けることができるため、他のリンクで提案されているカスタムペイントを行うよりも柔軟です。
StretchIcon.Java：
import Java.awt.Component;
import Java.awt.Container;
import Java.awt.Graphics;
import Java.awt.Graphics2D;
import Java.awt.Image;
import Java.awt.Insets;
import Java.awt.RenderingHints;
import Java.awt.image.BufferedImage;
import Java.awt.image.ImageObserver;
import Java.net.URL;
import javax.swing.ImageIcon;
/**
* An <CODE>Icon</CODE> that scales its image to fill the component area, excluding any border or insets, optionally maintaining the image's
* aspect ratio by padding and centering the scaled image horizontally or vertically.
* <P>
* The class is a drop-in replacement for <CODE>ImageIcon</CODE>, except that the no-argument constructor is not supported.
* <P>
* As the size of the Icon is determined by the size of the component in which it is displayed, <CODE>StretchIcon</CODE> must only be used
* in conjunction with a component and layout that does not depend on the size of the component's Icon.
*
* @version 1.1 01/15/2016
* @author Darryl
*/
public class StretchIcon extends ImageIcon
{
/**
*
*/
private static final long serialVersionUID = 1L;
/**
* Determines whether the aspect ratio of the image is maintained. Set to <code>false</code> to allow th image to distort to fill the
* component.
*/
protected boolean proportionate = true;
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
*
* @see ImageIcon#ImageIcon(byte[])
*/
public StretchIcon(byte[] imageData)
{
super(imageData);
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes with the specified behavior.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(byte[])
*/
public StretchIcon(byte[] imageData, boolean proportionate)
{
super(imageData);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(byte[], Java.lang.String)
*/
public StretchIcon(byte[] imageData, String description)
{
super(imageData, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes with the specified behavior.
*
* @see ImageIcon#ImageIcon(byte[])
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(byte[], Java.lang.String)
*/
public StretchIcon(byte[] imageData, String description, boolean proportionate)
{
super(imageData, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image.
*
* @param image the image
*
* @see ImageIcon#ImageIcon(Java.awt.Image)
*/
public StretchIcon(Image image)
{
super(image);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image with the specified behavior.
*
* @param image the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.awt.Image)
*/
public StretchIcon(Image image, boolean proportionate)
{
super(image);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image.
*
* @param image the image
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(Java.awt.Image, Java.lang.String)
*/
public StretchIcon(Image image, String description)
{
super(image, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image with the specified behavior.
*
* @param image the image
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.awt.Image, Java.lang.String)
*/
public StretchIcon(Image image, String description, boolean proportionate)
{
super(image, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file.
*
* @param filename a String specifying a filename or path
*
* @see ImageIcon#ImageIcon(Java.lang.String)
*/
public StretchIcon(String filename)
{
super(filename);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file with the specified behavior.
*
* @param filename a String specifying a filename or path
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.lang.String)
*/
public StretchIcon(String filename, boolean proportionate)
{
super(filename);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file.
*
* @param filename a String specifying a filename or path
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(Java.lang.String, Java.lang.String)
*/
public StretchIcon(String filename, String description)
{
super(filename, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file with the specified behavior.
*
* @param filename a String specifying a filename or path
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.awt.Image, Java.lang.String)
*/
public StretchIcon(String filename, String description, boolean proportionate)
{
super(filename, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL.
*
* @param location the URL for the image
*
* @see ImageIcon#ImageIcon(Java.net.URL)
*/
public StretchIcon(URL location)
{
super(location);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL with the specified behavior.
*
* @param location the URL for the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.net.URL)
*/
public StretchIcon(URL location, boolean proportionate)
{
super(location);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL.
*
* @param location the URL for the image
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(Java.net.URL, Java.lang.String)
*/
public StretchIcon(URL location, String description)
{
super(location, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL with the specified behavior.
*
* @param location the URL for the image
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(Java.net.URL, Java.lang.String)
*/
public StretchIcon(URL location, String description, boolean proportionate)
{
super(location, description);
this.proportionate = proportionate;
}
/**
* Paints the icon. The image is reduced or magnified to fit the component to which it is painted.
* <P>
* If the proportion has not been specified, or has been specified as <code>true</code>, the aspect ratio of the image will be preserved
* by padding and centering the image horizontally or vertically. Otherwise the image may be distorted to fill the component it is
* painted to.
* <P>
* If this icon has no image observer,this method uses the <code>c</code> component as the observer.
*
* @param c the component to which the Icon is painted. This is used as the observer if this icon has no image observer
* @param g the graphics context
* @param x not used.
* @param y not used.
*
* @see ImageIcon#paintIcon(Java.awt.Component, Java.awt.Graphics, int, int)
*/
@Override
public synchronized void paintIcon(Component c, Graphics g, int x, int y)
{
Image image = getImage();
if (image == null)
{
return;
}
Insets insets = ((Container) c).getInsets();
x = insets.left;
y = insets.top;
int w = c.getWidth() - x - insets.right;
int h = c.getHeight() - y - insets.bottom;
if (proportionate)
{
int iw = image.getWidth(c);
int ih = image.getHeight(c);
if ((iw * h) < (ih * w))
{
iw = (h * iw) / ih;
x += (w - iw) / 2;
w = iw;
}
else
{
ih = (w * ih) / iw;
y += (h - ih) / 2;
h = ih;
}
}
ImageObserver io = getImageObserver();
/*
* Added this code to generate nicer looking results when scaling. - bspkrs
* BEGIN CHANGES
*/
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g2d = bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, w, h, io == null ? c : io);
g2d.dispose();
/*
* END CHANGES
*/
g.drawImage(bi, x, y, w, h, io == null ? c : io);
}
/**
* Overridden to return 0. The size of this Icon is determined by the size of the component.
*
* @return 0
*/
@Override
public int getIconWidth()
{
return 0;
}
/**
* Overridden to return 0. The size of this Icon is determined by the size of the component.
*
* @return 0
*/
@Override
public int getIconHeight()
{
return 0;
}
}
private Image fitimage(Image img, int w, int h) {
int width = img.getWidth(this);
int height = img.getHeight(this);
BufferedImage resizedimage;
if (width > w && height > h) {
resizedimage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = resizedimage.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(img, 0, 0, w, h, null);
g2.dispose();
} else {
resizedimage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = resizedimage.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(img, 0, 0, width, height, null);
g2.dispose();
}
return resizedimage;
}
この機能を試してください：
public static BufferedImage resize(BufferedImage image, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, width, height, null);
g2d.dispose();
return bi;
}
BufferedImage image1=ImageIO.read(url.openStream());
BufferedImage resizedImage=resize(image,100,100);
System.out.println("Load image into frame...");
icon=new ImageIcon(resizedImage);