rt-thread/examples/gui/demo_view_dc_buffer.c

/*
 * 程序清单：DC Buffer演示
 *
 * 这个例子会在创建出的view上进行DC Buffer的演示
 */

#include "demo_view.h"
#include <rtgui/rtgui_system.h>
#include <rtgui/widgets/label.h>
#include <rtgui/widgets/slider.h>
#include <rtgui/image.h>

static rtgui_image_t *background;
static struct rtgui_dc *dc_buffer;

/*
 * view的事件处理函数
 */
static rt_bool_t dc_buffer_event_handler(struct rtgui_object *object, rtgui_event_t *event)
{
    struct rtgui_widget *widget = RTGUI_WIDGET(object);

    /* 仅对PAINT事件进行处理 */
    if (event->type == RTGUI_EVENT_PAINT)
    {
        struct rtgui_dc *dc;
        rtgui_rect_t rect;

        /*
         * 因为用的是demo view，上面本身有一部分控件，所以在绘图时先要让demo view
         * 先绘图
         */
        rtgui_container_event_handler(object, event);

        /* 获得控件所属的DC */
        dc = rtgui_dc_begin_drawing(widget);
        /* 如果不能正常获得DC，返回（如果控件或父控件是隐藏状态，DC是获取不成功的） */
        if (dc == RT_NULL)
            return RT_FALSE;

        /* 获得demo view允许绘图的区域 */
        demo_view_get_logic_rect(RTGUI_CONTAINER(widget), &rect);

        rect.x1 += 10;
        rect.y1 += 10;
        rtgui_dc_blit(dc_buffer, NULL, dc, &rect);

        /* 绘图完成 */
        rtgui_dc_end_drawing(dc);
    }
    else
    {
        /* 其他事件，调用默认的事件处理函数 */
        return rtgui_container_event_handler(object, event);
    }

    return RT_FALSE;
}

/* 创建用于DC Buffer操作演示用的视图 */
rtgui_container_t *demo_view_dc_buffer()
{
    rtgui_container_t *view;

    if (dc_buffer == RT_NULL)
    {
        rtgui_rect_t rect = {0, 0, 50, 50};

        /* 创建 DC Buffer，长 50，宽 50 */
        dc_buffer = rtgui_dc_buffer_create(50, 50);
        RTGUI_DC_FC(dc_buffer) = blue;
        rtgui_dc_fill_rect(dc_buffer, &rect);

        RTGUI_DC_FC(dc_buffer) = red;
        rtgui_dc_draw_circle(dc_buffer, 25, 25, 10);
    }

    view = demo_view("缓冲DC演示");
    if (view != RT_NULL)
        /* 设置成自己的事件处理函数 */
        rtgui_object_set_event_handler(RTGUI_OBJECT(view), dc_buffer_event_handler);

    return view;
}