org.eclipse.swt.graphics.Image
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java.lang.Object
Instances of this class are graphics which have been prepared for display on a specific device. That is, they are ready to paint using methods such as GC.drawImage() and display on widgets with, for example, Button.setImage().
If loaded from a file format that supports it, an Image may have transparency, meaning that certain pixels are specified as being transparent when drawn. Examples of file formats that support transparency are GIF and PNG.
There are two primary ways to use Images. The first is to load a graphic file from disk and create an Image from it. This is done using an Image constructor, for example:
Image i = new Image(device, "C:\\graphic.bmp");
A graphic file may contain a color table specifying which
colors the image was intended to possess. In the above example,
these colors will be mapped to the closest available color in
SWT. It is possible to get more control over the mapping of
colors as the image is being created, using code of the form:
ImageData data = new ImageData("C:\\graphic.bmp");
RGB[] rgbs = data.getRGBs();
// At this point, rgbs contains specifications of all
// the colors contained within this image. You may
// allocate as many of these colors as you wish by
// using the Color constructor Color(RGB), then
// create the image:
Image i = new Image(device, data);
Applications which require even greater control over the image loading process should use the support provided in class ImageLoader.
Application code must explicitely invoke the Image.dispose() method to release the operating system resources managed by each instance when those instances are no longer required.
| Field Summary | |
| int | handle
the handle to the OS image resource (Warning: This field is platform dependent) |
| int | type
specifies whether the receiver is a bitmap or an icon (one of SWT.BITMAP, SWT.ICON) |
| Constructor Summary | |
| Image(Device device,
ImageData data)
Constructs an instance of this class from the given ImageData. | |
| Image(Device device,
ImageData source,
ImageData mask)
Constructs an instance of this class, whose type is SWT.ICON, from the two given ImageData objects. | |
| Image(Device device,
Image srcImage,
int flag)
Constructs a new instance of this class based on the provided image, with an appearance that varies depending on the value of the flag. | |
| Image(Device device,
InputStream stream)
Constructs an instance of this class by loading its representation from the specified input stream. | |
| Image(Device device,
int width,
int height)
Constructs an empty instance of this class with the specified width and height. | |
| Image(Device device,
Rectangle bounds)
Constructs an empty instance of this class with the width and height of the specified rectangle. | |
| Image(Device device,
String filename)
Constructs an instance of this class by loading its representation from the file with the specified name. | |
| Method Summary | |
| void | dispose()
Disposes of the operating system resources associated with the image. |
| boolean | equals(Object object)
Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison. |
| Color | getBackground()
Returns the color to which to map the transparent pixel, or null if the receiver has no transparent pixel. |
| Rectangle | getBounds()
Returns the bounds of the receiver. |
| ImageData | getImageData()
Returns an ImageData based on the receiver Modifications made to this ImageData will not affect the Image. |
| int | hashCode()
Returns an integer hash code for the receiver. |
| void | internal_dispose_GC(int hDC,
GCData data)
Invokes platform specific functionality to dispose a GC handle. |
| int | internal_new_GC(GCData data)
Invokes platform specific functionality to allocate a new GC handle. |
| boolean | isDisposed()
Returns true if the image has been disposed, and false otherwise. |
| void | setBackground(Color color)
Sets the color to which to map the transparent pixel. |
| String | toString()
Returns a string containing a concise, human-readable description of the receiver. |
| static Image | win32_new(Device device,
int type,
int handle)
Invokes platform specific functionality to allocate a new image. |
| Methods inherited from class java.lang.Object |
| clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
|
Field Detail |
public int type
public int handle
| Constructor Detail |
public Image(Device device,
int width,
int height)
Image i = new Image(device, width, height);
GC gc = new GC(i);
gc.drawRectangle(0, 0, 50, 50);
gc.dispose();
Note: Some platforms may have a limitation on the size of image that can be created (size depends on width, height, and depth). For example, Windows 95, 98, and ME do not allow images larger than 16M.
public Image(Device device,
Image srcImage,
int flag)
public Image(Device device,
Rectangle bounds)
Image i = new Image(device, boundsRectangle);
GC gc = new GC(i);
gc.drawRectangle(0, 0, 50, 50);
gc.dispose();
Note: Some platforms may have a limitation on the size of image that can be created (size depends on width, height, and depth). For example, Windows 95, 98, and ME do not allow images larger than 16M.
public Image(Device device,
ImageData data)
public Image(Device device,
ImageData source,
ImageData mask)
The mask image should contain white wherever the icon is to be visible, and black wherever the icon is to be transparent. In addition, the source image should contain black wherever the icon is to be transparent.
public Image(Device device,
InputStream stream)
This constructor is provided for convenience when loading a single image only. If the stream contains multiple images, only the first one will be loaded. To load multiple images, use ImageLoader.load().
This constructor may be used to load a resource as follows:
new Image(device, clazz.getResourceAsStream("file.gif"));
public Image(Device device,
String filename)
This constructor is provided for convenience when loading a single image only. If the specified file contains multiple images, only the first one will be used.
| Method Detail |
public void dispose()
public boolean equals(Object object)
public Color getBackground()
There are certain uses of Images that do not support transparency (for example, setting an image into a button or label). In these cases, it may be desired to simulate transparency by using the background color of the widget to paint the transparent pixels of the image. Use this method to check which color will be used in these cases in place of transparency. This value may be set with setBackground().
public Rectangle getBounds()
public ImageData getImageData()
public int hashCode()
public int internal_new_GC(GCData data)
IMPORTANT: This method is not part of the public API for Image. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.
public void internal_dispose_GC(int hDC,
GCData data)
IMPORTANT: This method is not part of the public API for Image. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.
public boolean isDisposed()
This method gets the dispose state for the image. When an image has been disposed, it is an error to invoke any other method using the image.
public void setBackground(Color color)
There are certain uses of Images that do not support transparency (for example, setting an image into a button or label). In these cases, it may be desired to simulate transparency by using the background color of the widget to paint the transparent pixels of the image. This method specifies the color that will be used in these cases. For example:
Button b = new Button();
image.setBackground(b.getBackground());
b.setImage(image);
The image may be modified by this operation (in effect, the transparent regions may be filled with the supplied color). Hence this operation is not reversible and it is not legal to call this function twice or with a null argument.
This method has no effect if the receiver does not have a transparent pixel value.
public String toString()
public static Image win32_new(Device device,
int type,
int handle)
IMPORTANT: This method is not part of the public API for Image. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.
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