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
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 Group | Property Descriptions |
|---|---|
| Name | Name of the widget. Name is the unique identifier used in TouchGFX Designer and code. |
| Location | X 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. Visible specifies the visibility of the widget. Making the widget invisible also disables interacting with the widget through the screen.. |
| Style | Style specifies a predefined setup of the widget, that sets select properties to predefined values. These styles contain images that are free to use. |
| Image | Scaling Algorithm specifies the algorithm used for scaling the chosen image. Image specifies which image the widget should use. |
| Appearance | Alpha 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. |
| Mixins | Draggable 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 action | Description |
|---|---|
| Move widget | Move a widget to a new position over time. |
| Fade widget | Modify alpha value of widget over time. |
| Hide widget | Hides a widget (sets visibility to false). |
| Show widget | Make 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
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