Первые попытки рисовать

src/Canvas.zig

@@ -3,7 +3,9 @@ const builtin = @import("builtin");
 const dvui = @import("dvui");
 const Document = @import("models/Document.zig");
 const RenderEngine = @import("render/RenderEngine.zig").RenderEngine;
-const ImageRect = @import("models/basic_models.zig").ImageRect;
+const basic_models = @import("models/basic_models.zig");
+const ImageRect = basic_models.ImageRect;
+const ImageSize = basic_models.ImageSize;
 const Point2 = @import("models/basic_models.zig").Point2;
 const Color = dvui.Color;
 
@@ -25,6 +27,8 @@ _zoom: f32 = 1,
 _redraw_pending: bool = false,
 _last_redraw_time_ms: i64 = 0,
 cursor_document_point: ?Point2 = null,
+/// true — рисовать документ (render), false — пример (gradient/squares).
+draw_document: bool = true,
 
 pub fn init(allocator: std.mem.Allocator, document: *Document, engine: RenderEngine) Canvas {
     return .{
@@ -41,7 +45,7 @@ pub fn deinit(self: *Canvas) void {
     }
 }
 
-pub fn redrawExample(self: *Canvas) !void {
+fn redraw(self: *Canvas) !void {
     const full = self.getZoomedImageSize();
 
     const vis: ImageRect = self._visible_rect orelse ImageRect{ .x = 0, .y = 0, .w = 0, .h = 0 };
@@ -54,7 +58,11 @@ pub fn redrawExample(self: *Canvas) !void {
         return;
     }
 
-    const new_texture = self.render_engine.example(.{ .w = full.w, .h = full.h }, vis) catch null;
+    const canvas_size: ImageSize = .{ .w = full.w, .h = full.h };
+    const new_texture = if (self.draw_document)
+        self.render_engine.render(self.document, canvas_size, vis) catch null
+    else
+        self.render_engine.example(canvas_size, vis) catch null;
 
     if (new_texture) |tex| {
         if (self.texture) |old_tex| {
@@ -68,7 +76,7 @@ pub fn redrawExample(self: *Canvas) !void {
 
 pub fn exampleReset(self: *Canvas) !void {
     self.render_engine.exampleReset();
-    try self.redrawExample();
+    try self.redraw();
 }
 
 pub fn setZoom(self: *Canvas, value: f32) void {
@@ -88,14 +96,14 @@ pub fn processPendingRedraw(self: *Canvas) !void {
     if (!self._redraw_pending) return;
     if (self.redraw_throttle_ms == 0) {
         self._redraw_pending = false;
-        try self.redrawExample();
+        try self.redraw();
         return;
     }
     const now_ms = std.time.milliTimestamp();
     const elapsed: i64 = if (self._last_redraw_time_ms == 0) self.redraw_throttle_ms else now_ms - self._last_redraw_time_ms;
     if (elapsed < @as(i64, @intCast(self.redraw_throttle_ms))) return;
     self._redraw_pending = false;
-    try self.redrawExample();
+    try self.redraw();
 }
 
 pub fn getZoomedImageSize(self: Canvas) ImageRect {