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Docs: LCL/imglist. Updates topics based on forum suggestions.
* https://forum.lazarus.freepascal.org/index.php/topic,65576.0.html
* Updates:
* TCustomImageList.WidthForPPI
* TCustomImageList.Scaled
(cherry picked from commit b2b86ebaef)
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@ -1511,6 +1511,7 @@ TScaledImageListResolution is used in the implementation of the
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<seealso>
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<link id="TCustomImageListResolution"/>
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<link id="TCustomImageList.ResolutionForPPI"/>
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<link id="TCustomImageList.Scaled"/>
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<link id="TCustomImageList.DrawForPPI"/>
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</seealso>
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</element>
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@ -1567,7 +1568,7 @@ function.
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</p>
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<p>
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<var>AResolution</var> contains the <var>TCustomImageListResolution</var>
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instance with image data used as the source for the scaled images.
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instance with image data used as the source for the Scaled images.
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AResolution is stored in the <var>Resolution</var> property to provide access
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to its properties and methods in the scaled image resolution.
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</p>
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@ -2757,6 +2758,7 @@ GetResolutionForPPI is used in the implementation of the DrawForPPI method.
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<seealso>
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<link id="TScaledImageListResolution"/>
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<link id="TCustomImageList.Resolution"/>
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<link id="TCustomImageList.Scaled"/>
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<link id="TCustomImageList.DrawForPPI"/>
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</seealso>
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</element>
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@ -6113,12 +6115,12 @@ Width properties prior to adding images to the list.
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<element name="TCustomImageList.WidthForPPI">
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<short>
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Image width needed for the specified display density.
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Image width needed for the specified display density (PPI).
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</short>
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<descr>
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<p>
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<var>WidthForPPI</var> is an indexed read-only Integer property that contains
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the image width needed for images using the specified display density (Pixels
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the widths needed for images using the specified display densities (Pixels
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per Inch).
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</p>
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<p>
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@ -6133,7 +6135,10 @@ calculate the width of images.
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Reading the value for the property causes the image width to be calculated
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using the specified parameter values. If AWidth is 0 (zero) or a negative
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number, the value in the <var>Width</var> property is used as the initial
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image width. When <var>Scaled</var> contains <b>True</b>, the image width is
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image width.
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</p>
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<p>
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When <var>Scaled</var> contains <b>True</b>, the image width is
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calculated using the following formula:
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</p>
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<code>(AImageWidth * APPI) / 96</code>
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@ -6170,7 +6175,7 @@ and the value in AImageWidth is used as the property value.
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</p>
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<p>
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The <var>OnGetWidthForPPI</var> event handler is signalled (when assigned) to
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allow overriding the calculated image width. Applications can provide a
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allow the calculated image width to be overridden. Applications can provide a
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<var>TCustomImageListGetWidthForPPI</var> procedure which uses custom scaling
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logic, or performs simple image width substitution for given display
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densities.
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@ -6412,6 +6417,7 @@ using the specified display density.
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</descr>
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<seealso>
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<link id="TCustomImageListResolution"/>
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<link id="TCustomImageList.Scaled"/>
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<link id="TCustomImageList.Resolution"/>
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<link id="TCustomImageList.Resolutions"/>
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<link id="TCustomImageList.ResolutionsDesc"/>
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@ -6456,6 +6462,7 @@ GetResolutionForPPI (the read access specifier for the property).
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<seealso>
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<link id="TScaledImageListResolution"/>
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<link id="TCustomImageList.Resolution"/>
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<link id="TCustomImageList.Scaled"/>
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<link id="TCustomImageList.DrawForPPI"/>
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</seealso>
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</element>
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@ -6544,41 +6551,62 @@ resolutions are accessed in descending image size order in the enumerator.
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<short>Descending Resolutions enumerator for the class instance.</short>
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</element>
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<element name="TCustomImageList.Scaled">
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<short>
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Indicates if images are automatically scaled for missing resolutions.
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Controls whether image sizes are automatically scaled for different display
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density (Pixels per Inch) settings.
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</short>
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<descr>
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<p>
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<var>Scaled</var> is a <var>Boolean</var> property that indicates if images
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are automatically scaled for missing resolutions requested in the image list.
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The default value for the property is <b>False</b>.
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<var>Scaled</var> is a <var>Boolean</var> property used to enable or disable
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automatic scaling of image sizes for different resolutions (Pixels per Inch).
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</p>
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<p>
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When Scaled contains <b>True</b>, images in the list are dynamically scaled
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to the required width for a given display density (PPI). If the resolution
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already exists in the image list, it is used to retrieve images. If it does
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not already exist, an existing resolution is used as the basis for scaling
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images to the required width. When Scaled contains <b>False</b>, dynamic
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scaling is not performed for image resolutions. Instead, the closest
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resolution that matches the desired width is used as the source for images.
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When Scaled is <b>True</b>, images in the list are dynamically scaled from the
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Width and Height used in the image list to the size needed for a given display
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density (Pixels per Inch). If the scaled image size is one of the Resolutions
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found in the image list, the images in the Resolution are used. If an image
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size is needed that does not exist in Resolutions, the next smaller size is
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selected from the predefined images by using the WidthForPPI property and a
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specified PPI setting. The ResolutionForPPI property provides access to an
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image list using the scaled image size.
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</p>
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<p>
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Use the <var>OnGetWidthForPPI</var> event handler to perform image size
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overrides or substitution for a given display density (PPI).
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See <link id="TCustomImageList.WidthForPPI">WidthForPPI</link> for information
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about use of the pixels per inch setting to derive the scaling factor and the
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resulting size for images.
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</p>
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<p>
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When Scaled is <b>False</b>, images are not dynamically scaled. The Width and
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Height specified in the image list are used.
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</p>
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<p>
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The default value for the property is <b>False</b> and disables automatic
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scaling.
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</p>
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<p>
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At design-time, use the image list property editor to maintain images or
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resolutions used in the image list. At run-time, use the methods provided in
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the class instance to maintain the image list.
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</p>
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<p>
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Use the <var>OnGetWidthForPPI</var> event handler to override or substitute the
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image size used for a given display density (PPI).
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</p>
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<p>
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Scaled is used in the implementation of the <var>GetResolutionForPPI</var>
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and <var>GetWidthForPPI</var> methods.
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and <var>GetWidthForPPI</var> methods which implement the ResolutionForPPI and
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WidthForPPI properties (respectively).
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</p>
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</descr>
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<seealso>
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<link id="TCustomImageList.Resolution"/>
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<link id="TCustomImageList.Resolutions"/>
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<link id="TCustomImageList.ResolutionForPPI"/>
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<link id="TCustomImageList.WidthForPPI"/>
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<link id="TCustomImageList.OnGetWidthForPPI"/>
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<link id="TCustomImageList.FindResolution"/>
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<link id="TCustomImageList.Resolution"/>
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<link id="TCustomImageList.Resolutions"/>
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</seealso>
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</element>
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