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Version: 4.16

ScalableImage

ScalableImage is a widget capable of drawing a scaled version of a bitmap. Simply change the width/height of the widget to resize the image. The quality of the scaled image depends of the rendering algorithm used. The rendering algorithm can be changed dynamically.

Note
  • This widget has a significant effect on the MCU load.
  • This widget does not support 1 bit per pixel color depth.
  • ScalableImage running in the simulator

    Widget Group#

    The ScalableImage can be found in the Images widget group in TouchGFX Designer.

    ScalableImage in TouchGFX Designer

    Properties#

    The properties for a ScalableImage in TouchGFX Designer.

    Property GroupProperty Descriptions
    NameName of the widget. Name is the unique identifier used in TouchGFX Designer and code.
    LocationX and Y specify the top left corner of the widget relative to its parent.

    W and H specify the width and height of the widget.

    Lock specifies if the widget should be locked in its current X, Y, W and H.
    Locking the widget also disables interacting with the widget through the screen.

    Visible specifies the visibility of the widget. Making the widget invisible also disables interacting with the widget through the screen.
    StyleStyle specifies a predefined setup of the widget, that sets select properties to predefined values.
    These styles contain images that are free to use.
    ImageScaling Algorithm specifies the algorithm used for scaling the chosen image.

    Image specifies which image the widget should use.
    AppearanceAlpha specifies the transparency of the widget. The alpha value ranges between 0 and 255 for the widget. 0 is fully transparent and 255 is solid.
    MixinsDraggable specifies if the widget is draggable at runtime.

    ClickListener specifies if the widget emits a callback when clicked.

    FadeAnimator specifies if the widget can animate changes to its Alpha value.

    MoveAnimator specifies if the widget can animate changes to X and Y values.

    Interactions#

    The actions and triggers supported by a ScalableImage in TouchGFX Designer.

    Actions#

    Standard widget actionDescription
    Move widgetMove a widget to a new position over time.
    Fade widgetModify alpha value of widget over time.
    Hide widgetHides a widget (sets visibility to false).
    Show widgetMake a hidden widget visible (sets visibility to true).

    Triggers#

    A ScalableImage does not emit any triggers.

    Performance#

    A ScalableImage heavily depends upon the MCU for scaling the image. Therefore, the ScalableImage is considered a demanding widget on most platforms.

    For more details on drawing performance, read the read the General UI Component Performance section.

    Examples#

    Generated Code#

    In the generated code for the View base class we can see how the Designer sets up a ScalableImage.

    Screen1ViewBase.cpp
    #include <gui_generated/screen1_screen/Screen1ViewBase.hpp>
    #include "BitmapDatabase.hpp"
    Screen1ViewBase::Screen1ViewBase()
    {
    scalableImage.setBitmap(touchgfx::Bitmap(BITMAP_IMAGE_ID));
    scalableImage.setPosition(246, 36, 200, 200);
    scalableImage.setScalingAlgorithm(touchgfx::ScalableImage::NEAREST_NEIGHBOR);
    add(scalableImage);
    }
    void Screen1ViewBase::setupScreen()
    {
    }
    Tip
    You can use these functions and the others available in the ScalableImage class in user code. Remember to force a redraw by calling scalableImage.invalidate() if you change the appearance of the widget.

    TouchGFX Designer Examples#

    To further explore the ScalableImage, try creating a new application within TouchGFX Designer with one of the following UI templates:

    Scale and Zoom Example UI template in TouchGFX Designer

    API Reference#