ProgressivePasses property (ILEADRasterIO)
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short ProgressivePasses | |
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Overview |
Refer to Loading a Bitmap from a File. |
Remarks
Specifies the number of paint-while-load passes when the file is a progressive LEAD or JPEG file.
This property is also valid when reading (but not when writing) interlaced PNG files.
When the PaintWhileLoad property is TRUE, the full dimensions of the image can paint quickly on the first pass. Then, the image becomes progressively clearer on subsequent passes.
You can set this property before saving a LEAD or JPEG file to specify the possible number of passes. You can set it before loading a progressive LEAD or JPEG file (or an interlaced PNG file) to determine how many passes are actually used.
Technically, only files with more than three passes are progressive files. They include full color in the low-resolution first pass; subsequent passes improve the resolution. Files that contain two or three passes are multiscan files. They include grayscale information in the first pass, and color information in the subsequent pass or passes.
For information on progressive loading of JBIG files, refer to Implementing JBIG Features.
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Setting |
Description |
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0 |
(When saving) Save as an ordinary CMP or JPEG file, not a progressive file. |
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Any positive number |
(When saving or loading) Use the specified number of passes. |
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PROGRESSIVEPASSES_WHEN_MEANINGFUL |
(Only when loading) Stop painting when full clarity is achieved. |
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PROGRESSIVEPASSES_ALWAYS |
(Only when loading) Use the number of passes specified in the file being loaded. |
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PROGRESSIVEPASSES_ONCE |
(Only when loading) Paint once with full clarity. |
See Also
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Topics: |
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