lite源码阅读（二），开始

最新推荐文章于 2023-05-03 11:22:03 发布

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本文介绍如何从Lite库的example开始学习，通过实际代码展示了如何创建窗口、标签、文本行、按钮和图片等常见控件，并演示了按钮的响应事件。重点在于突出Lite库在构建简单GUI应用中的基本操作。

如果我们阅读uboot或linux内核会从Makefile入手，但是这里仅仅是一软件库而已，那我们就应该从example开始。

#include <config.h>

#include <stddef.h>

#include <lite/lite.h>
#include <lite/window.h>

#include <leck/button.h>
#include <leck/image.h>
#include <leck/label.h>
#include <leck/textline.h>

static void
button_pressed( LiteButton *button, void *ctx )
{
     lite_close_window( LITE_WINDOW(ctx) );
}

static void
toggle_button_pressed( LiteButton *button, void *ctx )
{
}

int
main (int argc, char *argv[])
{
     LiteButton   *button;
     LiteImage    *image;
     LiteLabel    *label;
     LiteTextLine *textline;
     LiteWindow   *window;
     DFBRectangle  rect;
     DFBResult     res;

     /* initialize */
     if (lite_open( &argc, &argv ))
          return 1;

     /* create a window */
     rect.x = LITE_CENTER_HORIZONTALLY;
     rect.y = LITE_CENTER_VERTICALLY;
     rect.w = 300;
     rect.h = 200;

     res = lite_new_window( NULL, 
                            &rect,
                            DWCAPS_ALPHACHANNEL, 
                            liteDefaultWindowTheme,
                            "Simple",
                            &window );


     /* setup the label */
     rect.x = 10; rect.y = 10; rect.w = 110;
     res = lite_new_label(LITE_BOX(window), &rect, liteNoLabelTheme, 20, &label);

     lite_set_label_text( label, "Hello World" );

     /* setup the textline */
     rect.x = 10; rect.y = 40; rect.w = 100; rect.h = 20;
     res = lite_new_textline(LITE_BOX(window), &rect, liteNoTextLineTheme, &textline);
     
     rect.x = 10; rect.y = 60; rect.w = 100; rect.h = 20;
     res = lite_new_textline(LITE_BOX(window), &rect, liteNoTextLineTheme, &textline);

     /* setup the button */
     rect.x = 180; rect.y = 130; rect.w = 50; rect.h = 50;
     res = lite_new_button(LITE_BOX(window), &rect, liteNoButtonTheme, &button);

     lite_set_button_image( button, LITE_BS_NORMAL, EXAMPLESDATADIR "/stop.png" );
     lite_set_button_image( button, LITE_BS_DISABLED, EXAMPLESDATADIR "/stop_disabled.png" );
     lite_set_button_image( button, LITE_BS_HILITE, EXAMPLESDATADIR "/stop_highlighted.png" );
     lite_set_button_image( button, LITE_BS_PRESSED, EXAMPLESDATADIR "/stop_pressed.png" );

     lite_on_button_press( button, button_pressed, window );
     
     /* 2nd button */
     rect.x = 230; rect.y = 130; rect.w = 50; rect.h = 50;
     res = lite_new_button(LITE_BOX(window), &rect, liteNoButtonTheme, &button);
     lite_set_button_type( button, LITE_BT_TOGGLE );
 
     lite_set_button_image( button, LITE_BS_NORMAL, EXAMPLESDATADIR "/toggle.png" );
     lite_set_button_image( button, LITE_BS_DISABLED, EXAMPLESDATADIR "/toggle_disabled.png" );
     lite_set_button_image( button, LITE_BS_HILITE, EXAMPLESDATADIR "/toggle_highlighted.png" );
     lite_set_button_image( button, LITE_BS_PRESSED, EXAMPLESDATADIR "/toggle_pressed.png" );
     lite_set_button_image( button, LITE_BS_HILITE_ON, EXAMPLESDATADIR "/toggle_highlighted_on.png" );
     lite_set_button_image( button, LITE_BS_DISABLED_ON, EXAMPLESDATADIR "/toggle_disabled_on.png" );

     lite_on_button_press( button, toggle_button_pressed, window );

     /* setup the image */
     rect.x = 200; rect.y = 20; rect.w = 64; rect.h = 50;
     res = lite_new_image(LITE_BOX(window), &rect, liteNoImageTheme, &image);

     lite_load_image( image, EXAMPLESDATADIR "/D.png" );


     /* show the window */
     lite_set_window_opacity( window, liteFullWindowOpacity );

     /* run the default event loop */
     lite_window_event_loop( window, 0 );

     /* destroy the window with all this children and resources */
     lite_destroy_window( window );

     /* deinitialize */
     lite_close();

     return 0;
}

lite包含了很多常见的控件，把其所有的控件的源码都介绍一下是没有意义的，在这里我们主要讲其基本内容和核心的技术。