| java.lang.Object
 com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.Image
| Image | | public class Image extends Widget implements SourcesClickEvents,SourcesLoadEvents,SourcesMouseEvents,SourcesMouseWheelEvents(Code) | | A widget that displays the image at a given URL. The image can be in
'unclipped' mode (the default) or 'clipped' mode. In clipped mode, a viewport
is overlaid on top of the image so that a subset of the image will be
displayed. In unclipped mode, there is no viewport - the entire image will be
visible. Whether an image is in clipped or unclipped mode depends on how the
image is constructed, and how it is transformed after construction. Methods
will operate differently depending on the mode that the image is in. These
differences are detailed in the documentation for each method.
If an image transitions between clipped mode and unclipped mode, any
Element -specific attributes added by the user (including style
attributes, style names, and style modifiers), except for event listeners,
will be lost.
CSS Style Rules
Tranformations between clipped and unclipped state will result in a loss of
any style names that were set/added; the only style names that are preserved
are those that are mentioned in the static CSS style rules. Due to
browser-specific HTML constructions needed to achieve the clipping effect,
certain CSS attributes, such as padding and background, may not work as
expected when an image is in clipped mode. These limitations can usually be
easily worked around by encapsulating the image in a container widget that
can itself be styled.
Example
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| Constructor Summary | |
| public | Image()
Creates an empty image. | | public | Image(String url)
Creates an image with a specified URL. | | public | Image(String url, int left, int top, int width, int height)
Creates a clipped image with a specified URL and visibility rectangle. |
| Image | | public Image()(Code) | | Creates an empty image.
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| Image | | public Image(String url)(Code) | | Creates an image with a specified URL. The load event will be fired once
the image at the given URL has been retrieved by the browser.
Parameters:
url - the URL of the image to be displayed |
| Image | | public Image(String url, int left, int top, int width, int height)(Code) | | Creates a clipped image with a specified URL and visibility rectangle. The
visibility rectangle is declared relative to the the rectangle which
encompasses the entire image, which has an upper-left vertex of (0,0). The
load event will be fired immediately after the object has been constructed
(i.e. potentially before the image has been loaded in the browser). Since
the width and height are specified explicitly by the user, this behavior
will not cause problems with retrieving the width and height of a clipped
image in a load event handler.
Parameters:
url - the URL of the image to be displayed
Parameters:
left - the horizontal co-ordinate of the upper-left vertex of thevisibility rectangle
Parameters:
top - the vertical co-ordinate of the upper-left vertex of thevisibility rectangle
Parameters:
width - the width of the visibility rectangle
Parameters:
height - the height of the visibility rectangle |
| getHeight | | public int getHeight()(Code) | | Gets the height of the image. When the image is in the unclipped state, the
height of the image is not known until the image has been loaded (i.e. load
event has been fired for the image).
the height of the image, or 0 if the height is unknown |
| getOriginLeft | | public int getOriginLeft()(Code) | | Gets the horizontal co-ordinate of the upper-left vertex of the image's
visibility rectangle. If the image is in the unclipped state, then the
visibility rectangle is assumed to be the rectangle which encompasses the
entire image, which has an upper-left vertex of (0,0).
the horizontal co-ordinate of the upper-left vertex of the image'svisibility rectangle |
| getOriginTop | | public int getOriginTop()(Code) | | Gets the vertical co-ordinate of the upper-left vertex of the image's
visibility rectangle. If the image is in the unclipped state, then the
visibility rectangle is assumed to be the rectangle which encompasses the
entire image, which has an upper-left vertex of (0,0).
the vertical co-ordinate of the upper-left vertex of the image'svisibility rectangle |
| getUrl | | public String getUrl()(Code) | | Gets the URL of the image. The URL that is returned is not necessarily the
URL that was passed in by the user. It may have been transformed to an
absolute URL.
the image URL |
| getWidth | | public int getWidth()(Code) | | Gets the width of the image. When the image is in the unclipped state, the
width of the image is not known until the image has been loaded (i.e. load
event has been fired for the image).
the width of the image, or 0 if the width is unknown |
| onBrowserEvent | | public void onBrowserEvent(Event event)(Code) | | |
| prefetch | | public static void prefetch(String url)(Code) | | Causes the browser to pre-fetch the image at a given URL.
Parameters:
url - the URL of the image to be prefetched |
| setUrl | | public void setUrl(String url)(Code) | | Sets the URL of the image to be displayed. If the image is in the clipped
state, a call to this method will cause a transition of the image to the
unclipped state. Regardless of whether or not the image is in the clipped
or unclipped state, a load event will be fired.
Parameters:
url - the image URL |
| setUrlAndVisibleRect | | public void setUrlAndVisibleRect(String url, int left, int top, int width, int height)(Code) | | Sets the url and the visibility rectangle for the image at the same time. A
single load event will be fired if either the incoming url or visiblity
rectangle co-ordinates differ from the image's current url or current
visibility rectangle co-ordinates. If the image is currently in the
unclipped state, a call to this method will cause a transition to the
clipped state.
Parameters:
url - the image URL
Parameters:
left - the horizontal coordinate of the upper-left vertex of thevisibility rectangle
Parameters:
top - the vertical coordinate of the upper-left vertex of thevisibility rectangle
Parameters:
width - the width of the visibility rectangle
Parameters:
height - the height of the visibility rectangle |
| setVisibleRect | | public void setVisibleRect(int left, int top, int width, int height)(Code) | | Sets the visibility rectangle of an image. The visibility rectangle is
declared relative to the the rectangle which encompasses the entire image,
which has an upper-left vertex of (0,0). Provided that any of the left,
top, width, and height parameters are different than the those values that
are currently set for the image, a load event will be fired. If the image
is in the unclipped state, a call to this method will cause a transition of
the image to the clipped state. This transition will cause a load event to
fire.
Parameters:
left - the horizontal coordinate of the upper-left vertex of thevisibility rectangle
Parameters:
top - the vertical coordinate of the upper-left vertex of thevisibility rectangle
Parameters:
width - the width of the visibility rectangle
Parameters:
height - the height of the visibility rectangle |
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