[Overview][Types][Classes][Procedures and functions][Index] | Reference for unit 'ImgList' (#lcl)

# TCustomImageList.WidthForPPI

Image width needed for the specified display density (PPI).

## Declaration

Source position: imglist.pp line 410

`public property TCustomImageList.WidthForPPI[AImageWidth: Integer,APPI: Integer] : Integer read GetWidthForPPI;`

## Description

WidthForPPI is an indexed read-only Integer property that contains the widths needed for images using the specified display densities (Pixels per Inch).

AImageWidth is an Integer value that contains the initial image width used for the calculated width at the specified display density.

APPI is an Integer value that contains the display density used to calculate the width of images.

Reading the value for the property causes the image width to be calculated using the specified parameter values. If AWidth is 0 (zero) or a negative number, the value in the Width property is used as the initial image width.

When Scaled contains True, the image width is calculated using the following formula:

    (AImageWidth * APPI) / 96

If an image resolution does not already exist which uses the derived image width, the display density in APPI is used as a threshold for scaling using the following criteria:

Display Density (PPI) | Scaling Factor (%)
96-120 | 100%
121-168 | 150%
169 and higher | Calculated using (APPI / 96) * 100

The property value contains the image width derived using the formula:

    AImageWidth * Factor div 100

When Scaled is False, image width scaling is not performed and the value in AImageWidth is used as the property value.

The OnGetWidthForPPI event handler is signalled (when assigned) to allow the calculated image width to be overridden. Applications can provide a TCustomImageListGetWidthForPPI procedure which uses custom scaling logic, or performs simple image width substitution for given display densities.

## See also

TCustomImageList.Scaled |  | Controls whether image sizes are automatically scaled for different display density (Pixels per Inch) settings.
TCustomImageList.OnGetWidthForPPI |  | Event handler used to override the scaled width for a display density.
TCustomImageListGetWidthForPPI |  | Specifies an event handler used to get image widths for a display density (PPI).