Clear the offscreen with white color and draw two red objects on it. Two objects have the same path but have different fill rules. Then blit this offscreen to the displayer that has a blue background.
If using the MIPI interface, connect the LCD displayer to J48 on the MIMXRT1170-EVK board. Connect 5V power to J43, set J38 to 1-2, and turn on the power switch SW5.
Now three LCD displayers are supported, which are defined in display_support.h:
#define DEMO_PANEL_RK055AHD091 0 /* 720 * 1280, RK055AHD091-CTG(RK055HDMIPI4M) */
#define DEMO_PANEL_RK055IQH091 1 /* 540 * 960, RK055IQH091-CTG */
#define DEMO_PANEL_RK055MHD091 2 /* 720 * 1280, RK055MHD091A0-CTG(RK055HDMIPI4MA0) */
Use the macro DEMO_PANEL to select the LCD panel you are using, the default panel is RK055AHD091-CTG configured in the display_support.h:
#define DEMO_PANEL DEMO_PANEL_RK055AHD091
For example, if your LCD panel is RK055MHD091A0-CTG, change the macro DEMO_PANEL definition as following:
#define DEMO_PANEL DEMO_PANEL_RK055MHD091
The source code is in FillRules.c, where the main function first configures clocks, pins, etc. freerots is deployed in the example. vglite_task is created and scheduled to execute VGLite initialization and drawing task.
Before drawing, several functions are executed to do initialization:
-
vg_lite_init
initializes VGLite and configures the tessellation buffer size, which is recommended to be the size of the most commonly rendered path size. In this project, it's defined by#define OFFSCREEN_BUFFER_WIDTH 400 #define OFFSCREEN_BUFFER_HEIGHT 400 error = vg_lite_init(OFFSCREEN_BUFFER_WIDTH, OFFSCREEN_BUFFER_HEIGHT);
-
vg_lite_set_command_buffer_size
sets the GPU command buffer size (optional). -
vg_lite_allocate
allocates the render buffer, whose the input parameter is vg_lite_buffer_t structure defining width, height, and color format, etc.
The path drawing opcodes (1st column) and arguments (other columns) are defined in the array pathData, such as
static int32_t pathData[] = {
2, 0, 400, //Move to (0, 400)
4, 200, 0, //Line from (0,400) to (200, 0)
4, 400, 400, //Line from (200, 0) to (400, 400)
4, 0, 400, //Line from (400, 400) to (0, 400)
2, 0, 0, //Move to (0, 0)
4, 400, 0, //Line from (0,0) to (400, 0)
4, 200, 400, //Line from (400, 0) to (400, 400)
4, 0, 0, //Line from (400, 400) to (0, 0)
0,
};
And vg_lite_path_t structure describes path data's bounding box, quality, coordinate format, etc., such as
static vg_lite_path_t path = {
{0, 0, // left,top
400, 400}, // right,bottom
VG_LITE_HIGH, // quality
VG_LITE_S32, //
{0}, // uploaded
sizeof(pathData), // path length
pathData, // path data
1 // path changed
};
In drawing task, there are following functions:
-
vg_lite_clear
clears the render buffer with a solid color (ABGR format). In this project, the rendered area is filled with white color byvg_lite_clear(&renderTarget, NULL, 0xFFFFFFFF);
And the full screen is filled with blue color by
vg_lite_clear(rt, NULL, 0xFFFF0000);
-
vg_lite_identity
resets the specified transformation matrix, which is uninitialized or previously modified by functions ofvg_lite_translate
,vg_lite_rotate
,vg_lite_scale
. -
vg_lite_draw
performs a 2D vector draw operation, drawing input path data with the specified fill rule, transformation matrix, blend mode, and fill color, etc. This project fills the path with red color, and different fill rules are applied to two objects separately:vg_lite_draw(&renderTarget, &path, VG_LITE_FILL_NON_ZERO, &matrix, VG_LITE_BLEND_NONE, 0xFF0000FF); vg_lite_draw(&renderTarget, &path, VG_LITE_FILL_EVEN_ODD, &matrix, VG_LITE_BLEND_NONE, 0xFF0000FF);
The fill rule is defined by the vg_lite_fill_t enumeration:
- VG_LITE_FILL_NON_ZERO: Non-zero fill rule. A pixel is drawn if it crosses at least one path pixel.
- VG_LITE_FILL_EVEN_ODD: Even-odd fill rule. A pixel is drawn if it crosses an odd number of path pixels.
-
vg_lite_translate
translates draw result by input coordinates with transformation matrix. In this project, two droppers are moved to different places byvg_lite_translate((DEMO_BUFFER_WIDTH - OFFSCREEN_BUFFER_WIDTH) / 2, 100, &matrix_blit); vg_lite_translate(0, DEMO_BUFFER_HEIGHT / 2, &matrix_blit);
-
vg_lite_blit
finally copies the source image to the destination window with the specified blend mode and filter mode, determining the showing of objects. In this project, VG_LITE_BLEND_SRC_OVER blend mode is selected to make source image placed on the background:error = vg_lite_blit(rt, &renderTarget, &matrix_blit, VG_LITE_BLEND_SRC_OVER, 0, mainFilter);
Once an error occurs, cleaning work is needed including the following functions:
-
vg_lite_free
frees the allocated render buffer.vg_lite_free(&renderTarget);
-
vg_lite_clear_path
clears path data uploaded to GPU memory.vg_lite_clear_path(&path);
-
vg_lite_close
finally frees up the entire memory initialized earlier by thevg_lite_init
function.vg_lite_close();
Compile firstly, and use a Micro-USB cable to connect PC to J86 on MIMXRT1170-EVK board, then download the firmware and run.
If it's successful, the correct image will show on the displayer:
And FPS information will be sent through UART serial port continuously. The correct UART configuration is
- 115200 baud rate
- 8 data bits
- No parity
- One stop bit
- No flow control