@@ -253,7 +253,7 @@ Notice the staff reference solution supports image pan and zoom behavior (drag t
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@@ -253,7 +253,7 @@ Notice the staff reference solution supports image pan and zoom behavior (drag t
A viewport defines a region of the SVG canvas that is visible in the app. The 3 properties we care about here are `centerX`, `centerY` and `vspan` (vertical span). They are all defined in normalized svg coordinate space.
A viewport defines a region of the SVG canvas that is visible in the app. The 3 properties we care about here are `centerX`, `centerY` and `vspan` (vertical span). They are all defined in normalized svg coordinate space.
When the application initially launches, the entire canvas is in view. When the application initially launches, the entire canvas is in view. For example, if the SVG canvas is of size 400x300, then the viewport will initially be centered on the canvas, and have a vertical field of view that spans the entire canvas. Specifically, the member values of the `Viewport` class will look like: `centerX=200, centerY=150`, and `vspan` is some number`>=150`.
When the application initially launches, the entire canvas is in view. For example, if the SVG canvas is of size 400x300, then the viewport will initially be centered on the canvas, and have a vertical field of view that spans the entire canvas. Specifically, the member values of the `Viewport` class will look like: `centerX=200, centerY=150`, and `vspan` is some number`>=150`.
When user actions require the viewport be changed, the application will call `update_viewbox()` with the appropriate parameters. Given this change in view parameters, you should implement `set_viewbox()` to compute and set transform `svg_2_norm` (by calling `set_svg_2_norm`) based on the new view parameters. This transform should map the SVG canvas coordinate space to a normalized device coordinate space where the top left of the visible SVG coordinate maps to `(0, 0)` and the bottom right maps to `(1, 1)`. For example, for the values `centerX=200, centerY=150, vspan=10`, then SVG canvas coordinate `(200, 150)` transforms to normalized coordinate `(0.5, 0.5)` (center of screen) and canvas coordinate `(200, 160)` transforms to `(0.5, 1)` (bottom center).
When user actions require the viewport be changed, the application will call `update_viewbox()` with the appropriate parameters. Given this change in view parameters, you should implement `set_viewbox()` to compute and set transform `svg_2_norm` (by calling `set_svg_2_norm`) based on the new view parameters. This transform should map the SVG canvas coordinate space to a normalized device coordinate space where the top left of the visible SVG coordinate maps to `(0, 0)` and the bottom right maps to `(1, 1)`. For example, for the values `centerX=200, centerY=150, vspan=10`, then SVG canvas coordinate `(200, 150)` transforms to normalized coordinate `(0.5, 0.5)` (center of screen) and canvas coordinate `(200, 160)` transforms to `(0.5, 1)` (bottom center).
