Page History: GDI Canvas Element
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Page Revision: 2011/07/14 15:42
GDI canvas is an element that allows you to create custom runtime graphics using the GDI+ functions. GDI+ is a powerful graphical platform in Windows, with thousands functions for drawing graphical primitives and bitmaps, managing colors and geometrical transforms (GDI+ overview). You can call these functions in your code snippets in order to draw a dynamic 2D graphical content in your experiment.
Element Description
Using the element is very easy. By setting its position and size you define a rectangular area on the screen that represents a rendering canvas for drawing functions. Then you address the Graphics property of the element. This property provides you with the base GDI class which, in turn, possesses all available drawing functions. Now you call these functions directly like in this C# line:
Graphics.DrawRectangle(new Pen(Color.Red), 20,20,248,162);
When a snippet with GDI calls is completed the canvas element redraws its rendering canvas which also reappears on the screen if the parent event is active.
- Note 1: The drawing coordinates in your code have to be inside of the range defined by the size of the GDI Canvas element in pixels, otherwise the drawn content will be cut off.
- Note 2: The GDI canvas element remembers its rendered state even if the parent event is deactivated and activated again. To clear the drawn graphics use the GDI Clear() function.
Properties of GDI canvas
| Name | Description | Attributes | Value Type |
|---|
| RunTime |
| Graphics | A reference of the base GDI+ class which implements all available drawing functions. | R | System.Drawing.Graphics |
+=== Properties inherited from clVisualElement ===
| Name | Description | Constraints | Value Type | Upon Runtime Change |
|---|
| VISUAL APPEARANCE |
| Alpha Masking | Defines whether the visual content rendered by this element will be used as an opacity mask which is applied onto the given event surface. The active opacity mask allows one to expose pixels of the parent event surface through a solid background of the given event. If the value is true, the darker pixels of the content will make more transparent holes on the entire event surface. | | Boolean | |
| AntiAliasing | If true, the rendered content will be anti-aliased for smoother visual appearance. If false, rendering will be authentic to its source, e.g. a bitmap. | | Boolean | |
| Position | Defines the position of the element viewport on the screen. The position can be set in any of three coordinate systems: a) pixels, b) polar, c) central. | | clPoint | |
| Size | Defines the size of the element viewport on the screen. The size can be set in any of three coordinate systems: a) pixels, b) visual degrees, c) 'relative-to-screen' size. | | clSize | |
| Z Order | Indicates the current depth order of the element viewport on the surface of the parent event. The greatest number corresponds to the top position. The order can be changed by moving the element up and down in the element list. | | Int32 | |
| Pivot Point | Defines the pivot point (coordinate and the rotation centers) within the element viewport. | | stAlignment or Int32 | |
| Visible | Defines whether the element is currently visible on the event surface. The property is convenient for switching visual content on and off. | | Boolean | |
| Rotation | Defines the rotation angle (in degrees) of element viewport relative to the its pivot point. | | Double in the range 0..360 | |
| EFFECTS |
| Transparent Color | The color of the original pixels of rendered content that will be set as transparent. | | stColor | |
| Transparency Tolerance | Tolerance ratio for choosing colors that become transparent. Zero means that effect is not applied, 1 denotes that all colors will become trasparent. | | Int32, range (0..100) | |
| Color Mask | Produces a multiplicative combination of the original pixels and the selected mask color (except the alpha channel). The effect emulates a look through a colored glass. White or transparent mask color doesn't change the original pixels. | | stColor | |
| Opacity | Opacity of the rendered content. | | Int32, range (0..100) | |
| Contrast | Contrast of the rendered content. | | Int32, range (-100..100) | |
| Brightness | Defines the brighness of the rendered content. | | Int32, range (-100..100) | |
| Saturation | Saturation of the rendered content. | | Double | |
| Pixelation | Defines the pixel scale of the rendering. | | Int32, range (0..100) | |
| Blurring | The radius used in the gaussian blur of rendered content, as a pixel-based factor. The default is 0 which means no blurring. | | Int32 | |
| POSITIONAL JITTER |
| Reset Jitter | Set to true at runtime to reset the current positional jitter. | | Boolean, set true for action | |
| Current Jitter | Jitter range, in pixels (non inclusive). | . | clSize | |
| Jitter Range | Jitter range, centered at the original position of the element. | . | clSize | |
+=== Properties inherited from clElement ===
Inherited properties of clElement
| Name | Description | Constraints | Value Type | Upon Change |
|---|
| Control |
| Is Enabled | If set to false the element is completely omitted when the experiment is run. | | Boolean |
|
| Title | Title of the element. | | String |
|
The list of Text element properties:
Resource Holder inherited properties
| CATEGORY ,Property name | Description | type | Value type |
| RESOURCE LIST |
| Resource index | The index of item in the resource list that is currently used by the element. Notice, that index starts from 1. | D,R,* | Int32 |
| Resource count | The number of items loaded in the resource list of the element | D,R,Read-only | Int32 |
|