35a3e3b8df9294a8ab30aac94f4d2d41a33bbb72
1 // Copyright (C) 2021 Harry Godden (hgn) - All Rights Reserved
3 SHADER_DEFINE( shader_ui
,
6 "layout (location=0) in vec2 a_co;" // i16, i16, .. ?
7 "layout (location=1) in vec2 a_uv;" // i8, i8
8 "layout (location=2) in vec4 a_colour;" // u32
9 "layout (location=3) in vec4 a_clip;" // i16, i16, i16, i16
12 "out vec2 aTexCoords;"
19 "gl_Position = vec4( uPv * vec3( a_co, 1.0 ), 1.0 );"
20 "aTexCoords = a_uv * 0.0078125;"
28 "uniform sampler2D uTexGlyphs;"
39 "float clip_blend = step( aWsp.x, aClip.z ) * step( aWsp.y, aClip.w ) * step( aClip.x, aWsp.x ) * step( aClip.y, aWsp.y );"
41 "vec4 glyph = texture( uTexGlyphs, aTexCoords );"
42 "FragColor = aColour * vec4( 1.0, 1.0, 1.0, glyph.r * clip_blend );"
45 UNIFORMS({ "uPv", "uTexGlyphs" })
48 #define UI_AUTO_FILL 0
52 // ===========================================================================================================
55 typedef u32 ui_colour
;
56 typedef ui_px ui_rect
[4];
57 typedef struct ui_ctx ui_ctx
;
98 int click_state
; // 0: released, 1: on down, 2: pressed, 3: on release
102 #define gui_draw(...) ui_draw( &ui_global_ctx, __VA_ARGS__)
103 #define gui_current(...) ui_current( &ui_global_ctx, __VA_ARGS__)
104 #define gui_new_node() ui_new_node( &ui_global_ctx )
105 #define gui_hasmouse(...) ui_hasmouse( &ui_global_ctx, __VA_ARGS__)
106 #define gui_end() ui_end( &ui_global_ctx )
107 #define gui_end_down() ui_end_down( &ui_global_ctx )
108 #define gui_end_right() ui_fill_right( &ui_global_ctx )
109 #define gui_fill_y() ui_fill_y( &ui_global_ctx)
110 #define gui_fill_x() ui_fill_x( &ui_global_ctx)
111 #define gui_align_bottom() ui_align_bottom( &ui_global_ctx )
112 #define gui_align_right() ui_align_right( &ui_global_ctx )
113 #define gui_align_top() ui_align_top( &ui_global_ctx )
114 #define gui_align_left() ui_align_left( &ui_global_ctx )
115 #define gui_clamp_rect(...) ui_clamp_rect( &ui_global_ctx, __VA_ARGS__)
116 #define gui_group_id(...) ui_group_id( &ui_global_ctx, __VA_ARGS__)
117 #define gui_capture_mouse(...) ui_capture_mouse( &ui_global_ctx, __VA_ARGS__)
118 #define gui_set_clip(...) ui_set_clip( &ui_global_ctx, __VA_ARGS__)
119 #define gui_release_clip() ui_release_clip( &ui_global_ctx )
120 #define gui_fill_rect_uv(...) ui_fill_rect_uv( &ui_global_ctx, __VA_ARGS__)
121 #define gui_fill_rect(...) ui_fill_rect( &ui_global_ctx, __VA_ARGS__)
122 #define gui_text(...) ui_text( &ui_global_ctx, __VA_ARGS__)
123 #define gui_begin(...) ui_begin( &ui_global_ctx, __VA_ARGS__)
124 #define gui_resolve(...) ui_resolve( &ui_global_ctx, __VA_ARGS__)
125 #define gui_set_mouse(...) ui_set_mouse( &ui_global_ctx, __VA_ARGS__)
126 #define gui_button(...) ui_button( &ui_global_ctx, __VA_ARGS__)
127 #define gui_window(...) ui_window( &ui_global_ctx, __VA_ARGS__)
128 #define gui_want_mouse() ui_want_mouse( &ui_global_ctx )
131 // ===========================================================================================================
134 int ui_glyph_override
= 0;
135 ui_px ui_glyph_spacing_x
= 6;
136 GLuint ui_glyph_texture
= 0;
141 #define UI_BUFFER_SIZE 30000
142 #define UI_INDEX_SIZE 20000
144 ui_ctx ui_global_ctx
= { .padding
= 8 };
148 // ===========================================================================================================
150 static void ui_override_font( GLuint new_tex
, ui_px space_x
)
152 if( ui_glyph_texture
)
153 glDeleteTextures( 1, &ui_glyph_texture
);
155 ui_glyph_texture
= new_tex
;
156 ui_glyph_override
= 1;
157 ui_glyph_spacing_x
= space_x
;
160 static void ui_default_init(void)
163 if( !ui_glyph_override
)
166 #include "fonts/weiholmir.h"
169 u32 pixels
= 0, total
= 72*72, data
= 0;
170 u8
*image
= malloc( total
);
172 while( pixels
< total
)
174 for( int b
= 31; b
>= 0; b
-- )
176 image
[ pixels
++ ] = (compressed
[data
] & (0x1 << b
))? 0xff: 0x00;
178 if( pixels
>= total
)
187 glGenTextures( 1, &ui_glyph_texture
);
188 glBindTexture( GL_TEXTURE_2D
, ui_glyph_texture
);
190 glTexImage2D( GL_TEXTURE_2D
, 0, GL_R8
, 72, 72, 0, GL_RED
, GL_UNSIGNED_BYTE
, image
);
198 // Setup OpenGL memory
200 SHADER_INIT( shader_ui
);
202 // Generate the buffer we are gonna be drawing to
203 glGenVertexArrays(1, &ui_vao
);
204 glGenBuffers( 1, &ui_vbo
);
205 glGenBuffers( 1, &ui_ebo
);
206 glBindVertexArray( ui_vao
);
208 glBindBuffer( GL_ARRAY_BUFFER
, ui_vbo
);
210 glBufferData( GL_ARRAY_BUFFER
, UI_BUFFER_SIZE
* sizeof( struct ui_vert
), NULL
, GL_DYNAMIC_DRAW
);
211 glBindVertexArray( ui_vao
);
213 glBindBuffer( GL_ELEMENT_ARRAY_BUFFER
, ui_ebo
);
214 glBufferData( GL_ELEMENT_ARRAY_BUFFER
, UI_INDEX_SIZE
* sizeof( u16
), NULL
, GL_DYNAMIC_DRAW
);
216 u32
const stride
= sizeof( struct ui_vert
);
219 glVertexAttribPointer( 0, 2, GL_SHORT
, GL_FALSE
, stride
, (void *)offsetof( struct ui_vert
, co
) );
220 glEnableVertexAttribArray( 0 );
223 glVertexAttribPointer( 1, 2, GL_UNSIGNED_BYTE
, GL_FALSE
, stride
, (void *)offsetof( struct ui_vert
, uv
) );
224 glEnableVertexAttribArray( 1 );
227 glVertexAttribPointer( 2, 4, GL_UNSIGNED_BYTE
, GL_TRUE
, stride
, (void *)offsetof( struct ui_vert
, colour
) );
228 glEnableVertexAttribArray( 2 );
231 glVertexAttribPointer( 3, 4, GL_SHORT
, GL_FALSE
, stride
, (void *)offsetof( struct ui_vert
, clip
) );
232 glEnableVertexAttribArray( 3 );
235 // Initialize default context
237 ui_global_ctx
.verts
= (struct ui_vert
*)malloc( UI_BUFFER_SIZE
* sizeof(struct ui_vert
) );
238 ui_global_ctx
.indices
= (u16
*)malloc( UI_INDEX_SIZE
* sizeof(u16
) );
242 static void ui_default_free(void)
244 if( !ui_glyph_override
)
245 glDeleteTextures( 1, &ui_glyph_texture
);
247 glDeleteVertexArrays( 1, &ui_vao
);
248 glDeleteBuffers( 1, &ui_vbo
);
249 glDeleteBuffers( 1, &ui_ebo
);
251 free( ui_global_ctx
.verts
);
252 free( ui_global_ctx
.indices
);
255 static void ui_draw( ui_ctx
*ctx
, m3x3f view_override
)
257 glBindVertexArray( ui_vao
);
259 glBindBuffer( GL_ARRAY_BUFFER
, ui_vbo
);
260 glBufferSubData( GL_ARRAY_BUFFER
, 0, ctx
->num_verts
* sizeof( struct ui_vert
), ctx
->verts
);
262 glBindBuffer( GL_ELEMENT_ARRAY_BUFFER
, ui_ebo
);
263 glBufferSubData( GL_ELEMENT_ARRAY_BUFFER
, 0, ctx
->num_indices
* sizeof( u16
), ctx
->indices
);
266 glBlendFunc(GL_SRC_ALPHA
, GL_ONE_MINUS_SRC_ALPHA
);
267 glBlendEquation(GL_FUNC_ADD
);
269 SHADER_USE( shader_ui
);
271 m3x3f view
= M3X3_IDENTITY
;
275 view_override
= view
;
277 m3x3_translate( view
, (v3f
){ -1.0f
, 1.0f
, 0.0f
} );
278 m3x3_scale( view
, (v3f
){ 1.0f
/((float)vg_window_x
*0.5f
), -1.0f
/((float)vg_window_y
*0.5f
), 1.0f
} );
281 glUniformMatrix3fv( SHADER_UNIFORM( shader_ui
, "uPv" ), 1, GL_FALSE
, (float *)view_override
);
283 glActiveTexture( GL_TEXTURE0
);
284 glBindTexture( GL_TEXTURE_2D
, ui_glyph_texture
);
285 glUniform1i( SHADER_UNIFORM( shader_ui
, "uTexGlyphs" ), 0 );
287 glDrawElements( GL_TRIANGLES
, ctx
->num_indices
, GL_UNSIGNED_SHORT
, (void*)(0) );
289 //vg_info( "Verts: %u, Indices: %u\n", ctx->num_verts, ctx->num_indices );
295 // ===========================================================================================================
297 static void ui_rect_copy( ui_rect src
, ui_rect dst
)
305 static void ui_rect_pad( ui_rect rect
, ui_px pad
)
313 static void ui_vis_rect( ui_rect rect
, u32 colour
)
321 p1
[0] = rect
[0]+rect
[2];
322 p1
[1] = rect
[1]+rect
[3];
324 vg_line( p0
, (v2f
){p1
[0],p0
[1]}, colour
);
325 vg_line( (v2f
){p1
[0],p0
[1]}, p1
, colour
);
326 vg_line( p1
, (v2f
){p0
[0],p1
[1]}, colour
);
327 vg_line( (v2f
){p0
[0],p1
[1]}, p0
, colour
);
332 // ===========================================================================================================
334 static struct ui_qnode
*ui_current( ui_ctx
*ctx
)
336 return &ctx
->stack
[ ctx
->stack_count
-1 ];
339 static void ui_new_node( ui_ctx
*ctx
)
341 if( ctx
->stack_count
== vg_list_size( ctx
->stack
) )
342 vg_exiterr( "[UI] Stack overflow while creating box!" );
344 struct ui_qnode
*parent
= &ctx
->stack
[ ctx
->stack_count
-1 ];
345 struct ui_qnode
*node
= &ctx
->stack
[ ctx
->stack_count
++ ];
346 ui_rect_copy( ctx
->cursor
, node
->rect
);
348 if( parent
->mouse_over
)
350 if( ctx
->mouse
[0] >= node
->rect
[0] && ctx
->mouse
[0] <= node
->rect
[0]+node
->rect
[2] &&
351 ctx
->mouse
[1] >= node
->rect
[1] && ctx
->mouse
[1] <= node
->rect
[1]+node
->rect
[3] )
352 node
->mouse_over
= 1;
354 node
->mouse_over
= 0;
358 node
->mouse_over
= 0;
362 static int ui_hasmouse( ui_ctx
*ctx
)
364 struct ui_qnode
*node
= ui_current( ctx
);
365 return (node
->mouse_over
&& (node
->capture_id
== ctx
->capture_mouse_id
));
368 static void ui_end( ui_ctx
*ctx
)
370 struct ui_qnode
*node
= &ctx
->stack
[ --ctx
->stack_count
];
372 ui_rect_copy( node
->rect
, ctx
->cursor
);
373 ui_vis_rect( ctx
->cursor
,
374 (node
->mouse_over
&& (node
->capture_id
== ctx
->capture_mouse_id
))? 0xffff0000: 0xff0000ff );
377 static void ui_end_down( ui_ctx
*ctx
)
379 ui_px height
= ui_current( ctx
)->rect
[3];
381 ctx
->cursor
[1] += height
;
384 static void ui_end_right( ui_ctx
*ctx
)
386 ui_px width
= ui_current( ctx
)->rect
[2];
388 ctx
->cursor
[0] += width
;
391 static void ui_fill_y( ui_ctx
*ctx
)
393 struct ui_qnode
*node
= ui_current( ctx
);
394 ctx
->cursor
[3] = node
->rect
[3] - (ctx
->cursor
[1]-node
->rect
[1]);
397 static void ui_fill_x( ui_ctx
*ctx
)
399 struct ui_qnode
*node
= ui_current( ctx
);
400 ctx
->cursor
[2] = node
->rect
[2] - (ctx
->cursor
[0]-node
->rect
[0]);
403 // Alignment: | [] | -> | []|
404 static void ui_align_bottom( ui_ctx
*ctx
)
406 struct ui_qnode
*node
= ui_current( ctx
);
407 ctx
->cursor
[1] = node
->rect
[1] + node
->rect
[3] - ctx
->cursor
[3];
410 static void ui_align_right( ui_ctx
*ctx
)
412 struct ui_qnode
*node
= ui_current( ctx
);
413 ctx
->cursor
[0] = node
->rect
[0] + node
->rect
[2] - ctx
->cursor
[2];
416 static void ui_align_top( ui_ctx
*ctx
)
418 ctx
->cursor
[1] = ui_current( ctx
)->rect
[1];
421 static void ui_align_left( ui_ctx
*ctx
)
423 ctx
->cursor
[0] = ui_current( ctx
)->rect
[0];
426 static void ui_clamp_rect( ui_rect parent
, ui_rect dest
)
428 dest
[0] = vg_min( parent
[0] + parent
[2] - dest
[2], dest
[0] );
429 dest
[1] = vg_min( parent
[1] + parent
[3] - dest
[3], dest
[1] );
430 dest
[0] = vg_max( parent
[0], dest
[0] );
431 dest
[1] = vg_max( parent
[1], dest
[1] );
434 static u32
ui_group_id( ui_ctx
*ctx
, u32 lesser_unique
)
436 return ctx
->id_base
| lesser_unique
;
439 static void ui_capture_mouse( ui_ctx
*ctx
, u32 id
)
441 u32 group_uid
= ui_group_id(ctx
,id
);
443 struct ui_qnode
*node
= &ctx
->stack
[ ctx
->stack_count
-1 ];
444 node
->capture_id
= group_uid
;
446 if( !ctx
->capture_lock
&& node
->mouse_over
)
448 ctx
->capture_mouse_id
= group_uid
;
452 static int ui_want_mouse( ui_ctx
*ctx
)
454 return ctx
->capture_mouse_id
== 0? 0: 1;
457 static void ui_set_clip( ui_ctx
*ctx
, ui_rect clip
)
459 ctx
->clipping
[0] = clip
[0];
460 ctx
->clipping
[1] = clip
[1];
461 ctx
->clipping
[2] = clip
[0] + clip
[2];
462 ctx
->clipping
[3] = clip
[1] + clip
[3];
465 static void ui_release_clip( ui_ctx
*ctx
)
467 ctx
->clipping
[0] = -32000;
468 ctx
->clipping
[1] = -32000;
469 ctx
->clipping
[2] = 32000;
470 ctx
->clipping
[3] = 32000;
474 // ===========================================================================================================
476 static struct ui_vert
*ui_fill_rect_uv( ui_ctx
*ctx
, ui_rect rect
, u32 colour
, ui_px uv
[4] )
478 struct ui_vert
*vertices
= &ctx
->verts
[ ctx
->num_verts
];
479 vertices
[0].co
[0] = rect
[0];
480 vertices
[0].co
[1] = rect
[1];
481 vertices
[0].uv
[0] = uv
[0];
482 vertices
[0].uv
[1] = uv
[1];
483 vertices
[0].colour
= colour
;
484 vertices
[1].co
[0] = rect
[0]+rect
[2];
485 vertices
[1].co
[1] = rect
[1];
486 vertices
[1].uv
[0] = uv
[2];
487 vertices
[1].uv
[1] = uv
[1];
488 vertices
[1].colour
= colour
;
489 vertices
[2].co
[0] = rect
[0]+rect
[2];
490 vertices
[2].co
[1] = rect
[1]+rect
[3];
491 vertices
[2].uv
[0] = uv
[2];
492 vertices
[2].uv
[1] = uv
[3];
493 vertices
[2].colour
= colour
;
494 vertices
[3].co
[0] = rect
[0];
495 vertices
[3].co
[1] = rect
[1]+rect
[3];
496 vertices
[3].uv
[0] = uv
[0];
497 vertices
[3].uv
[1] = uv
[3];
498 vertices
[3].colour
= colour
;
499 u16 ind_start
= ctx
->num_verts
;
500 u16
*indices
= &ctx
->indices
[ ctx
->num_indices
];
502 ui_rect_copy( ctx
->clipping
, vertices
[0].clip
);
503 ui_rect_copy( ctx
->clipping
, vertices
[1].clip
);
504 ui_rect_copy( ctx
->clipping
, vertices
[2].clip
);
505 ui_rect_copy( ctx
->clipping
, vertices
[3].clip
);
507 indices
[0] = ind_start
+0;
508 indices
[1] = ind_start
+2;
509 indices
[2] = ind_start
+1;
511 indices
[3] = ind_start
+0;
512 indices
[4] = ind_start
+3;
513 indices
[5] = ind_start
+2;
515 ctx
->num_indices
+= 6;
521 static struct ui_vert
*ui_fill_rect( ui_ctx
*ctx
, ui_rect rect
, u32 colour
)
523 return ui_fill_rect_uv( ctx
, rect
, colour
, (ui_px
[4]){ 4,124,4,124 } );
526 static void ui_text( ui_ctx
*ctx
, const char *str
, ui_px scale
, int alignment
)
530 text_cursor
[0] = ctx
->cursor
[0];
531 text_cursor
[1] = ctx
->cursor
[1];
532 text_cursor
[2] = scale
*8;
533 text_cursor
[3] = scale
*8;
535 u32 current_colour
= ctx
->override_colour
;
537 const char *_c
= str
;
539 while( (c
= *(_c
++)) )
543 text_cursor
[1] += 10*scale
;
544 text_cursor
[0] = ctx
->cursor
[0];
547 else if( c
>= 33 && c
<= 126 )
550 u8 glyph_index
= c
- 32;
551 glyph_base
[0] = glyph_index
&0xf;
552 glyph_base
[1] = (glyph_index
-glyph_base
[0])>>4;
557 ui_fill_rect_uv( ctx
, text_cursor
, current_colour
,
562 128-(glyph_base
[1]+8)
565 else if( c
== '\x1B' )
569 for( int i
= 0; i
< 3; i
++ )
579 case '0': current_colour
= 0xffffffff; break;
580 case '3'|'1'<<8: current_colour
= 0xff201fee; break;
581 case '3'|'2'<<8: current_colour
= 0xff37e420; break;
582 case '3'|'3'<<8: current_colour
= 0xff0ed8e2; break;
583 case '3'|'4'<<8: current_colour
= 0xfff15010; break;
584 case '3'|'5'<<8: current_colour
= 0xffee20ee; break;
585 case '3'|'6'<<8: current_colour
= 0xffeeee20; break;
586 case '3'|'7'<<8: current_colour
= 0xffffffff; break;
592 colour_id
|= _c
[i
] << (i
*8);
603 text_cursor
[0] += (ui_glyph_spacing_x
*scale
)/2;
608 // ====================================================================
610 static void ui_begin( ui_ctx
*ctx
, ui_px res_x
, ui_px res_y
)
614 ctx
->cursor
[2] = res_x
;
615 ctx
->cursor
[3] = res_y
;
617 ui_rect_copy( ctx
->cursor
, ctx
->stack
[0].rect
);
618 ctx
->stack
[0].mouse_over
= 1;
620 ctx
->stack_count
= 1;
623 ctx
->num_indices
= 0;
625 ui_release_clip( ctx
);
627 if( ctx
->click_state
== 0 )
628 ctx
->capture_mouse_id
= 0;
631 static void ui_resolve( ui_ctx
*ctx
)
633 if( ctx
->stack_count
-1 )
634 vg_exiterr( "[UI] Mismatched node create/drestroy!" );
636 if( ctx
->click_state
== 3 || ctx
->click_state
== 0 )
638 ctx
->capture_lock
= 0;
643 // ====================================================================
645 static void ui_set_mouse( ui_ctx
*ctx
, int x
, int y
, int click_state
)
650 ctx
->click_state
= click_state
;
653 // High level controls
654 // ====================================================================
662 ui_px drag_offset
[2];
667 k_button_released
= 0,
668 k_button_start_click
,
673 static int ui_button( ui_ctx
*ctx
, u32 id
)
677 ui_capture_mouse( ctx
, id
);
679 if( ui_hasmouse(ctx
) )
681 ui_fill_rect( ctx
, ctx
->cursor
, 0xffcccccc );
683 if( ctx
->click_state
== 1 )
685 ctx
->capture_lock
= 1;
686 return k_button_start_click
;
688 else if( ctx
->capture_lock
&& ctx
->click_state
== 3 )
689 return k_button_click
;
690 else if( ctx
->capture_lock
&& ctx
->click_state
== 2 )
691 return k_button_hold
;
694 ui_fill_rect( ctx
, ctx
->cursor
, 0xff999999 );
697 return k_button_released
;
700 static int ui_window( ui_ctx
*ctx
, struct ui_window
*window
, u32 control_group
)
702 ctx
->id_base
= control_group
<< 16;
706 window
->transform
[0] = ctx
->mouse
[0]+window
->drag_offset
[0];
707 window
->transform
[1] = ctx
->mouse
[1]+window
->drag_offset
[1];
709 ui_clamp_rect( ctx
->stack
[0].rect
, window
->transform
);
711 if( ctx
->click_state
== 0 || ctx
->click_state
== 3 )
717 ui_rect_copy( window
->transform
, ctx
->cursor
);
721 ui_capture_mouse( ctx
, __COUNTER__
);
727 ui_capture_mouse( ctx
, __COUNTER__
);
729 struct ui_vert
*drag_bar
= ui_fill_rect( ctx
, ctx
->cursor
, 0xff555555 );
734 ui_text( ctx
, window
->title
, 2, 0 );
739 ui_align_right( ctx
);
741 ui_rect_pad( ctx
->cursor
, 4 );
743 if( ui_button( ctx
, __COUNTER__
) )
745 vg_info( "Click clacked\n" );
748 ui_text( ctx
, "x", 2, 0 );
751 if( ui_hasmouse( ctx
) )
753 drag_bar
[0].colour
= 0xff777777;
754 drag_bar
[1].colour
= 0xff777777;
755 drag_bar
[2].colour
= 0xff777777;
756 drag_bar
[3].colour
= 0xff777777;
759 if( ctx
->click_state
== 1 )
762 window
->drag_offset
[0] = window
->transform
[0]-ctx
->mouse
[0];
763 window
->drag_offset
[1] = window
->transform
[1]-ctx
->mouse
[1];
783 static void ui_scrollbar( ui_ctx
*ctx
, struct ui_scrollbar
*scrollbar
, u32 id
)
785 scrollbar
->view_height
= ctx
->cursor
[3];
787 if( scrollbar
->drag
)
789 scrollbar
->py
= ctx
->mouse
[1]+scrollbar
->drag_offset
;
790 scrollbar
->py
= VG_MAX( scrollbar
->py
, 0 );
791 scrollbar
->py
= VG_MIN( scrollbar
->py
, ctx
->cursor
[3] - scrollbar
->bar_height
);
793 if( ctx
->click_state
== 0 || ctx
->click_state
== 3 )
799 ui_fill_rect( ctx
, ctx
->cursor
, 0xff000000 );
800 ui_capture_mouse( ctx
, __COUNTER__
);
802 ctx
->cursor
[1] += scrollbar
->py
;
803 ctx
->cursor
[3] = scrollbar
->bar_height
;
807 ui_capture_mouse( ctx
, __COUNTER__
);
808 struct ui_vert
*drag_bar
= ui_fill_rect( ctx
, ctx
->cursor
, 0xff555555 );
810 if( ui_hasmouse( ctx
) || scrollbar
->drag
)
812 drag_bar
[0].colour
= 0xff777777;
813 drag_bar
[1].colour
= 0xff777777;
814 drag_bar
[2].colour
= 0xff777777;
815 drag_bar
[3].colour
= 0xff777777;
818 if( ctx
->click_state
== 1 )
821 scrollbar
->drag_offset
= scrollbar
->py
- ctx
->mouse
[1];
830 static ui_px
ui_calculate_content_scroll( struct ui_scrollbar
*scrollbar
, ui_px content
)
832 float overlap
= vg_maxf( 0.0f
, (float)(content
- scrollbar
->view_height
) );
834 float range
= scrollbar
->view_height
- scrollbar
->bar_height
;
835 return ((float)scrollbar
->py
/ range
) * overlap
;