The class subsection specifies the default values for window properties.
Windows must be associated with a display. Therefore, include this section in your configuration file only if your system supports displays, or if there are applications on your system that require them. This class section must begin with begin class class_name and end with end class.
The class subsection is used to set default values for the window properties defined within the section; these properties are specified through parameters applied to framebuffers and application windows.
The number of class subsections that can be defined for framebuffers depends on the number of displays available. Screen allows one framebuffer per display.
You can use the following convention to specify that a class subsection is used for a framebuffer:
framebufferunique_string
The class_name of the class subsection must start with the string framebuffer, then followed by a unique string to identify the class. For example, some valid class name strings are:
begin class framebuffer1
display = 1
pipeline = 1
format = rgba8888
usage = pvr2d
id_string = fb1
end class
begin class framebuffer2
display = 2
pipeline = 2
format = rgba8888
usage = pvr2d
id_string = fb2
end class
There's no explicit limit on the number of class subsections that can be defined for configuring application windows.
The class_name of the class subsection must be a unique string. This string must also match the window property, SCREEN_PROPERTY_CLASS, that you set in your application.
begin class my_app_properties
visible = true
surface-size = 640x480
source-position = 0,0
source-size = 640x480
window-position = 0,0
window-size = 640x480
end class
If you use the above class subsection in your configuration file, then you need to set the SCREEN_PROPERTY_CLASS window property in your application code. The setting of this property triggers Screen to apply the configured values that are associated with that class to your application window.
...
const char *my_win_class = "my_app_properties";
screen_set_window_property_cv(screen_win, SCREEN_PROPERTY_CLASS, strlen(my_win_class), my_win_class);
...
instead of this:
...
const int visible = 1
const int buffer_size[2] = { 640, 480};
const int src_pos[2] = { 0, 0};
const int src_size[2] = { 640, 480};
const int win_pos[2] = { 0, 0};
const int win_size[2] = { 640, 480};
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_VISIBLE, &visible);
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_BUFFER_SIZE, buffer_size);
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_SOURCE_POSITION, src_pos);
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_SOURCE_SIZE, src_size);
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_POSITION, win_pos);
screen_set_window_property_iv(screen_win, SCREEN_PROPERTY_SIZE, win_size);
...
to set your window properties.
Properties that can be set only when SCREEN_PROPERTY_SELF_LAYOUT has been enabled are referred to as layout-related properties. These properties (and the SCREEN_PROPERTY_SELF_LAYOUT property) of application windows are set by their manager. See SCREEN_PROPERTY_SELF_LAYOUT from Screen property types for more information on layout-related properties.
Application windows can set their layout-related properties only in the following cases:
However, when applications windows set their SCREEN_PROPERTY_CLASS property using a predefined class from graphics.conf, all the properties configured in that predefined class are applied.
From the above example, the class, "my_app_properties", configures (among others) the following parameters:
These parameters change layout-related properties. In this case, they're configured in a predefined class ("my_app_properties") in graphics.conf. Therefore, they're applied when, at runtime, the application window sets its SCREEN_PROPERTY_CLASS property to "my_app_properties".
If there is a manager running on the system, it will be notified of these property changes.
The following are valid parameters that can be configured under the class subsection:
| Parameter | Description | Type | Possible value(s) |
|---|---|---|---|
| alpha-mode | The method of alpha blending to use for alpha compositing. | String |
|
| brightness | The brightness of a window. This configuration depends on the hardware. That is, the brightness can be configured, but whether or not it takes effect is determined by your hardware. | Integer | -255 to 255 |
| buffer-count | The number of buffers that are to be created or attached to a window. Beyond configuration, you can't set the buffer count; you can only query it. There's no explicit limit for this count. The default is 3. | Long Integer | 0 to 4294967295
Example: 3 |
| cbabc | Content-based automatic brightness control; specifies the content type of a window. This configuration depends on the hardware. That is, cbabc can be configured, but whether or not it takes effect is determined by your hardware. | String |
none video ui photo |
| clip-position | The x- and y- position of a clipped rectangular viewport within the window buffers. This configuration must be in the form x-position,y-position. | Integer | 0 to 4294967295, 0 to 4294967295 Example:100,100 |
| clip-size | The width and height (in pixels) of a clipped rectangular viewport within the window buffers. This configuration must be in the form widthxheight. | Integer | 0 to 4294967295 x 0 to 4294967295 Example: 100x100 |
| color | The background color of a window. Use RGB color code (HEX value) to identify the color. (e.g., blue = 0xff). | unsigned long integer (hex) | 0x00 (default: black) |
| contrast | The contrast adjustment of a window. This configuration depends on the hardware; it can be configured, but may or may not take effect as determined by your hardware. | Integer | -128 to 127 |
| display | The connection type to the display or the display on which the window will be shown. If the configuration is an integer, Screen interprets it as the ID of the display. Otherwise, if the configuration is a string that matches one of the valid display connection types, then Screen interprets the string as the display connection type. | String or integer |
internal composite svideo YPbPr rgb rgbhv dvi hdmi 1..2 |
| format | The pixel format used by a window. Only one format is expected; this format must be supported by the display. | String |
byte (default) rgba4444 rgbx4444 rgba5551 rgbx5111 rgb565 rgb888 rgba8888 rgbx8888 yvu9 yuv420 nv12 yv12 uyvy yuy2 v422 ayuv |
| global-alpha | The global alpha mode to apply to a window | Integer | 0 to 225 |
| hue | The hue adjustment of a window | Integer | -128 to 127 |
| id_string | A string to identify the contents of a window | String | |
| interval | The minimum number of vsync periods between posts | Unsigned long integer | 0 to 4294967295 |
| order | The z-order of a window. It's the distance from the bottom that's used when ordering windows and window groups amongst each other. | Long integer | –2,147,483,648 to 2,147,483,647 |
| permissions | The permissions applied to a window. You can set multiple permissions by separating each valid permission by a comma. See "Permissions and Privileges" for valid permission strings. | String | |
| pipeline | The pipeline identifier. This must refer to a pipeline defined in the wfd device section of the configuration file and depends on the board you are using. | Unsigned long integer | 1 to 3 are valid values |
| rotation | The clockwise rotation, in degrees, of a window. Window rotation is absolute. | Long integer |
0 90 180 270 |
| saturation | The saturation adjustment of a window | Integer | -128 to 127 |
| sensitivity |
The sensitivity that a window has to input events (e.g., touch, pointer). The sensitivity is comprised of one or more strings representing valid sensitivity masks. Valid strings are:
When multiple sensitivity masks are configured, each mask in the configuration must be separated by a comma or space (e.g., sensitivity = no_focus, fullscreen). The resulting sensitivity applied to the window is the bitwise OR of all the valid sensitivity masks that are configured with this parameter. If you don't specfiy this sensitivity parameter in your configuration file, Screen defaults to behaving as follows:
|
String |
|
| source-position | The x and y coordinates of the top-left corner of a rectangular region within the window buffer that represents the source viewport of a window. This is the portion of the window buffer that's to be displayed. This configuration must be in the form x-position,y-position. | Integer | 0 to 4294967295, 0 to 4294967295 For example: 100, 100 |
| source-size | The width and height (in pixels) of a region within the window buffer that represents the source viewport of the window. This is the portion of the window buffer that's to be displayed. This configuration must be in the form widthxheight. | Integer | 0 to 4294967295 x 0 to 4294967295 For example: 100x100 |
| static | The indicator of whether the contents of a window are expected to change | Unsigned long integer |
|
| surface-size | The width and height of the window buffer. This configuration must be in the form widthxheight. | Integer | 0 to 4294967295 x 0 to 4294967295 For example: 100x100 |
| usage |
The intended usage for the window buffers and/or the composition module ( the module used for composition
onto a framebuffer). You can configure this parameter using any combination of the following:
How you configure this usage parmeter has implications on the composition module that Screen loads and uses:
When multiple usage flags are configured, each flag in the configuration must be
separated by a comma or space. You can combine the composition module name with the usage flags in the
same configuration line as long as they're separated by a comma or a space.
For example, the following are examples of valid entries for
configuring usage:
When multiple usage flags that imply composition modules are set, Screen
determines the composition module based on the following priorities (from highest to lowest):
For example, if your usage configuration is: usage = gles1 2 pvr2d, you're
specifying a user-provided composition module pvr2d, as well as setting the following usage flags:
|
String |
|
| visible | The indicator of whether or not a window is visible | String |
true (visible) false (not visible) |
| window-position | The x and y positions of the window screen coordinates. Remember that the position of child and embedded windows are relative to the parent window. For example, if the position of the application window is (10, 10) and the position of the child window is (10, 10), then the position of the child window on the screen is actually (20, 20). This configuration must be in the form x-position,y-position. | Integer | 0 to 4294967295, 0 to
4294967295 For example:10,10 |
| window-size | The width and height (in pixels) of a window. This configuration must be in the form widthxheight. | Integer | 0 to 4294967295 x 0 to 4294967295 For example: 100x100 |