beginUpdate Method (ImageViewer)
Summary
Stops the viewer from updating the transformations matrices, view layout and rendering the content if any change is applied. This is useful to increase the control's speed efficiency.
Syntax
JavaScript Syntax
ImageViewer.prototype.beginUpdate = function()TypeScript Syntax
beginUpdate(): void;Remarks
The BeginUpdate method will cause the control to not update the image viewing transformation or invalidate the display when any changes to the control's properties or the image is applied. When the user calls the EndUpdate method, the viewer will then update the transformation and invalidate the display to show all the changes that have been made.
For better visual results and for speed efficiency, it is recommended you surround multiple calls that will cause a render or transformation change between BeginUpdate and EndUpdate.
Calls to BeginUpdate and EndUpdate are accumulative. Each call to BeginUpdate must be matched with a corresponding call to EndUpdate or else updates to the transform won't be applied.
When the final EndUpdate is called and updating is resumed, the viewer will call UpdateTransform and Invalidate to re-calculate the transformations matrices and layout and render the new content.
BeginUpdate will call BeginRender and BeginTransform while EndUpdate will call EndRender and EndTransform. The most common usage of stopping the viewer from updating will usually involve disabling both transformations update and rendering. If only rendering or only transformation is to be disabled for a specific need, then use BeginRender and BeginTransform individually.
For more information, refer to Image Viewer Rendering.
Example
For an example, refer to Items.
Requirements
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© 1991-2017 LEAD Technologies, Inc. All Rights Reserved.
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