Skip to content

Latest commit

 

History

History
152 lines (103 loc) · 5.32 KB

README.md

File metadata and controls

152 lines (103 loc) · 5.32 KB

evkmimxrt1170_11_FreeSizeBuffers

Clear an offscreen with white color and draw five buffers with different sizes and colors, then blit it to the center of display that has a black background.

Hardware Preparation

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.

Software Preparation

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 FreeSizeBuffers.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.

VGLite Initialization

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.

In this project, the vg_lite_buffer_t structure array buffers[5] is defined, and corresponding arrays, such as strangeBufferValues[5], offsetValues[5], clearColorValues[5], are created to define the size, Y coordinate, and color of five members of buffers[5]:

vg_lite_buffer_t buffers[5];

unsigned int strangeBufferValues[5] = {107, 83, 137, 181, 79};

unsigned int offsetValues[5];

unsigned int clearColorValues[5] = {0xFF0000FF, 0xFFFF0000, 0xFF00FF00, 0xFFFF00FF, 0xFF00FFFF};

offsetValues[0] = 20;
offsetValues[1] = offsetValues[0] + 73;
offsetValues[2] = offsetValues[1] + 73;
offsetValues[3] = offsetValues[2] + 73;
offsetValues[4] = offsetValues[3] + 73;

And five width values and five color values are applied to the corresponding buffer in the following code:

for(i = 0; i < 5; i++)
{
    buffers[i].width = strangeBufferValues[i];
    buffers[i].height = 53;
    buffers[i].format = VG_LITE_RGBA8888;

    error = vg_lite_allocate(&buffers[i]);
}

Drawing Task

Since there is no path to be drawn, the array pathData and vg_lite_path_t structure is not used in this project. 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 by

    vg_lite_clear(&renderTarget, NULL, 0xFFFFFFFF);

    And five buffers are cleared with specified colors, shown in the following key code:

    for(i = 0; i < 5; i++)
{
    vg_lite_clear(&buffers[i], NULL, clearColorValues[i]);
}

  • vg_lite_identity resets the specified transformation matrix, which is uninitialized or previously modified by functions of vg_lite_translate, vg_lite_rotate, vg_lite_scale.

  • vg_lite_translate translates draw result by input coordinates with transformation matrix.

  • 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, a for loop function is used to blit five buffers to different positions:

for(i = 0; i < 5; i++)
{
    vg_lite_identity(&matrix);
    vg_lite_translate(10, offsetValues[i], &matrix);
    error = vg_lite_blit(&renderTarget, &buffers[i], &matrix, 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 buffers.

    for(i = 0; i < 5; i++)
{
    vg_lite_free(&buffers[i]);
}
vg_lite_free(&renderTarget);

  • vg_lite_close finally frees up the entire memory initialized earlier by the vg_lite_init function.

    vg_lite_close();

Run

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:

evkmimxrt1170_11_FreeSizeBuffers

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