Add constraint step fill_crop() to address purely theoretical double rounding issue

Author: lilith

imageflow_riapi/src/sizing.rs

@@ -229,6 +229,16 @@ impl Layout {
             ..self
         })
     }
+    pub fn fill_crop(self, target: AspectRatio) -> Result<Layout> {
+        let new_source = target.box_of(&self.source, BoxKind::Inner)?;
+        Ok(Layout {
+            source: new_source,
+            image: target,
+            canvas: target,
+            ..self
+        })
+
+    }
 
     //Also distorts 'image' in a corresponding fashion.
     pub fn distort_canvas(self, target: AspectRatio) -> Result<Layout> {
@@ -323,6 +333,7 @@ impl Layout {
         match step {
             Step::None | Step::BeginSequence | Step::SkipIf(_) | Step::SkipUnless(_) => Ok(self),
             Step::ScaleToOuter => self.scale_canvas(self.target, BoxKind::Outer),
+            Step::FillCrop => self.fill_crop(self.target),
             Step::ScaleToInner => self.scale_canvas(self.target, BoxKind::Inner),
             Step::PadAspect => self.pad_canvas(self.target.box_of(&self.canvas, BoxKind::Outer)?),
             Step::Pad => self.pad_canvas(self.target),
@@ -493,6 +504,8 @@ pub enum Step {
     Crop, //What about intersect? Crop that doesn't fail out of bounds
     CropToIntersection,
     CropAspect,
+    /// Use ScaleToOuterAndCrop instead of ScaleToOuter, then Crop, because the combination can reduce the dimensions below the outer box
+    FillCrop,
     /// We can use a variety of hints, and we're not required to fully change the aspect ratio or achieve the target box
     PartialCrop,
     PartialCropAspect,
@@ -562,6 +575,10 @@ impl StepsBuilder {
         self.steps.push(Step::ScaleToOuter);
         self
     }
+    pub fn fill_crop(mut self) -> StepsBuilder {
+        self.steps.push(Step::FillCrop);
+        self
+    }
     pub fn distort(mut self, t: BoxParam) -> StepsBuilder {
         self.steps.push(Step::Distort(t));
         self

imageflow_riapi/src/sizing_tests.rs

@@ -88,12 +88,12 @@ fn strategy_to_steps(s: Strategy) -> Option<Vec<Step>> {
 
         //Scale_to_outer can reduce the width, then crop the height, causing both coordinates to be smaller
         //TODO: perhaps combine scale_to_outer and crop() into a single operation to prevent this?
-        Strategy::CropOrAspect => { steps().skip_if(Cond::Either(Ordering::Less)).scale_to_outer().crop()
+        Strategy::CropOrAspect => { steps().skip_if(Cond::Either(Ordering::Less)).fill_crop()
             .new_seq().skip_unless(Cond::Either(Ordering::Less)).crop_aspect() },
 
 
         //I think we need multiple parts, as we don't offer a way to compare against the obox
-        Strategy::CropDownscaleOnly => { steps().skip_if(Cond::Either(Ordering::Less)).scale_to_outer().crop().new_seq().skip_unless(Cond::Larger1DSmaller1D).crop_intersection() },
+        Strategy::CropDownscaleOnly => { steps().skip_if(Cond::Either(Ordering::Less)).fill_crop().new_seq().skip_unless(Cond::Larger1DSmaller1D).crop_intersection() },
         //        Strategy::CropCarefulDownscale => StepSet::AnyLarger(vec![Step::ScaleToOuter,
         //        Step::PartialCropAspect, Step::ScaleToInner]),
         //        Strategy::ExactCropAllowUpscaling => StepSet::Always(vec![Step::ScaleToOuter,
@@ -591,7 +591,7 @@ fn test_scale_to_outer(){
 #[test]
 fn test_scale_to_outer_and_crop(){
     let cropper = sizing::IdentityCropProvider::new();
-    let result = Layout::create(r(2,4), r(1,3)).execute_all(&steps().scale_to_outer().crop().into_vec(), &cropper).unwrap();
+    let result = Layout::create(r(2,4), r(1,3)).execute_all(&steps().fill_crop().into_vec(), &cropper).unwrap();
     assert_eq!(result.get_source_crop(), r(1,4))
 }
 
@@ -995,4 +995,4 @@ static SMALL_PRIMES:[i32;1000] = [
 ,7573,7577,7583,7589,7591,7603,7607,7621,7639,7643
 ,7649,7669,7673,7681,7687,7691,7699,7703,7717,7723
 ,7727,7741,7753,7757,7759,7789,7793,7817,7823,7829
-,7841,7853,7867,7873,7877,7879,7883,7901,7907,7919];
+,7841,7853,7867,7873,7877,7879,7883,7901,7907,7919];