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Keep the overlay on the photograph when the view moves

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The overlay is a source-space picture; the canvas beside it shows whatever
the crop, the zoom and the pan selected out of that same space. Drawn whole
it stayed frame-sized while the photograph moved underneath, so zooming in
left a map of the whole picture stretched over a detail of it.

It now reports the visible rectangle as a clip, which the compositor
applies for nothing. Resampling on the CPU instead would mean rebuilding a
megapixel image on every frame of a drag, and putting it on the GPU would
add a second texture to keep in step with the view.

Pushed from the render path rather than the panel's sync: a pan changes no
mask and no row, so nothing else needs to run, and rebuilding the row
models on every frame of a drag would be waste.

Straightening is handled by rotating the image. A quarter turn or a flip
permutes the axes and a clip rectangle cannot say that — noted where it
happens rather than left to be discovered. The proper fix is to run the
overlay through the same shader prologue the photograph goes through, which
is the right answer and a larger one than this.

Four tests, and the one that matters asserts the clip *narrows* when zoomed
— which is precisely what it failed to do.
This commit is contained in:
dtourolle
2026-08-22 08:53:02 +02:00
parent 37f63edbf9
commit e7dbdeb21f
4 changed files with 201 additions and 5 deletions
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ui/dr-ui/ui/app.slint
+19
View File
@@ -806,6 +806,15 @@ export component AppWindow inherits Window {
/// opaque map hides the thing being judged.
in property <float> overlay-strength: 0.55;
in property <bool> overlay-on: false;
/// Which part of the source-space overlay the view is showing, in overlay
/// pixels. Without it the overlay stays frame-sized while the photograph
/// moves under it.
in property <int> overlay-clip-x;
in property <int> overlay-clip-y;
in property <int> overlay-clip-w;
in property <int> overlay-clip-h;
/// The straightening angle, so the overlay turns with the frame.
in property <float> overlay-angle: 0.0;
/// Clicking the canvas selects a region instead of panning.
in property <bool> region-picking: false;
/// Whether shift is down, tracked by the develop key scope below.
@@ -1336,6 +1345,16 @@ in property <bool> panel-visible: true;
width: parent.shown-w;
height: parent.shown-h;
source: root.region-overlay;
// The visible part of a source-space picture, which is
// what makes the overlay follow a zoom, a pan and a
// crop. The compositor does the crop and the scale;
// resampling on the CPU would mean rebuilding a
// megapixel image on every frame of a drag.
source-clip-x: root.overlay-clip-x;
source-clip-y: root.overlay-clip-y;
source-clip-width: root.overlay-clip-w;
source-clip-height: root.overlay-clip-h;
rotation-angle: -root.overlay-angle * 1deg;
image-fit: fill;
opacity: root.overlay-strength;
// Nearest-neighbour, always. The map is proxy-sized