Зум к курсору

src/Canvas.zig

@@ -88,6 +88,10 @@ pub fn addZoom(self: *Canvas, value: f32) void {
     self._zoom = @max(self._zoom, 0.01);
 }
 
+pub fn getZoom(self: Canvas) f32 {
+    return self._zoom;
+}
+
 pub fn requestRedraw(self: *Canvas) void {
     self._redraw_pending = true;
 }
@@ -116,23 +120,27 @@ pub fn getZoomedImageSize(self: Canvas) Rect_i {
     };
 }
 
-pub fn contentPointToDocument(self: Canvas, content_point: dvui.Point, natural_scale: f32) ?Point2_f {
+/// Возвращает координаты точки контента в координатах документа. Всегда возвращает точку,
+/// даже если она за пределами документа
+pub fn contentPointToDocument(self: Canvas, content_point: dvui.Point, natural_scale: f32) Point2_f {
+    const img = self.getZoomedImageSize();
+    const px_x = content_point.x * natural_scale - @as(f32, @floatFromInt(img.x));
+    const px_y = content_point.y * natural_scale - @as(f32, @floatFromInt(img.y));
+    return .{
+        .x = px_x / self._zoom,
+        .y = px_y / self._zoom,
+    };
+}
+
+/// Возвращает true, если точка контента лежит внутри холста (документа).
+pub fn isContentPointOnDocument(self: Canvas, content_point: dvui.Point, natural_scale: f32) bool {
     const img = self.getZoomedImageSize();
     const left_n = @as(f32, @floatFromInt(img.x)) / natural_scale;
     const top_n = @as(f32, @floatFromInt(img.y)) / natural_scale;
     const right_n = @as(f32, @floatFromInt(img.x + img.w)) / natural_scale;
     const bottom_n = @as(f32, @floatFromInt(img.y + img.h)) / natural_scale;
-
+    return content_point.x >= left_n and content_point.x < right_n and
-    if (content_point.x < left_n or content_point.x >= right_n or
+        content_point.y >= top_n and content_point.y < bottom_n;
-        content_point.y < top_n or content_point.y >= bottom_n)
-        return null;
-
-    const px_x = content_point.x * natural_scale - @as(f32, @floatFromInt(img.x));
-    const px_y = content_point.y * natural_scale - @as(f32, @floatFromInt(img.y));
-    return Point2_f{
-        .x = px_x / self._zoom,
-        .y = px_y / self._zoom,
-    };
 }
 
 pub fn updateVisibleImageRect(self: *Canvas, viewport: dvui.Rect, scroll_offset: dvui.Point) bool {

src/ui/canvas_view.zig

@@ -99,15 +99,39 @@ fn handleCanvasZoom(canvas: *Canvas, scroll: anytype) void {
     const ctrl = dvui.currentWindow().modifiers.control();
     if (!ctrl) return;
 
+    const natural_scale = if (canvas.native_scaling) 1 else dvui.windowNaturalScale();
+
     for (dvui.events()) |*e| {
         switch (e.evt) {
-            .mouse => |mouse| {
+            .mouse => |*mouse| {
                 const action = mouse.action;
                 if (dvui.eventMatchSimple(e, scroll.data()) and (action == .wheel_x or action == .wheel_y)) {
                     switch (action) {
                         .wheel_y => |y| {
+                            const viewport_pt = scroll.data().contentRectScale().pointFromPhysical(mouse.p);
+                            const content_pt = dvui.Point{
+                                .x = viewport_pt.x + canvas.scroll.viewport.x,
+                                .y = viewport_pt.y + canvas.scroll.viewport.y,
+                            };
+                            const doc_pt = canvas.contentPointToDocument(content_pt, natural_scale);
+
                             canvas.addZoom(y / 1000);
                             canvas.requestRedraw();
+
+                            // Сдвигаем viewport так, чтобы точка под курсором (даже вне холста) не уезжала
+                            const new_zoom = canvas.getZoom();
+                            const img = canvas.getZoomedImageSize();
+                            const new_content_x = (@as(f32, @floatFromInt(img.x)) + doc_pt.x * new_zoom) / natural_scale;
+                            const new_content_y = (@as(f32, @floatFromInt(img.y)) + doc_pt.y * new_zoom) / natural_scale;
+                            canvas.scroll.viewport.x = new_content_x - viewport_pt.x;
+                            canvas.scroll.viewport.y = new_content_y - viewport_pt.y;
+                            const viewport_rect = scroll.data().contentRect();
+                            const content_w = @as(f32, @floatFromInt(img.x + img.w)) / natural_scale;
+                            const content_h = @as(f32, @floatFromInt(img.y + img.h)) / natural_scale;
+                            const max_x = @max(0, content_w - viewport_rect.w + canvas.pos.x);
+                            const max_y = @max(0, content_h - viewport_rect.h + canvas.pos.y);
+                            canvas.scroll.viewport.x = std.math.clamp(canvas.scroll.viewport.x, 0, max_x);
+                            canvas.scroll.viewport.y = std.math.clamp(canvas.scroll.viewport.y, 0, max_y);
                         },
                         else => {},
                     }
@@ -133,7 +157,8 @@ fn handleCanvasMouse(canvas: *Canvas, scroll: anytype) void {
                     .x = viewport_pt.x + canvas.scroll.viewport.x,
                     .y = viewport_pt.y + canvas.scroll.viewport.y,
                 };
-                canvas.cursor_document_point = canvas.contentPointToDocument(content_pt, natural_scale);
+                const doc_pt = canvas.contentPointToDocument(content_pt, natural_scale);
+                canvas.cursor_document_point = if (canvas.isContentPointOnDocument(content_pt, natural_scale)) doc_pt else null;
                 if (canvas.cursor_document_point) |point|
                     std.debug.print("cursor_document_point: {}\n", .{point});
             },