#350 better computation of ratios, landscape ratios

lazpaint/dialog/unewimage.lfm

@@ -116,22 +116,6 @@ object FNewImage: TFNewImage
     Top = 103
     Width = 63
     ItemHeight = 15
-    Items.Strings = (
-      ''
-      '1:1'
-      '6:5'
-      '5:4'
-      '4:3'
-      '11:8'
-      '1.414:1'
-      '1.43:1'
-      '3:2'
-      '8:5'
-      '1.618:1'
-      '5:3'
-      '16:9'
-      '2:1'
-    )
     MaxLength = 12
     OnChange = ComboBox_RatioChange
     OnEnter = ComboBox_RatioEnter

lazpaint/dialog/unewimage.pas

@@ -14,6 +14,10 @@ const
   shadowOffsetX = 3;
   shadowOffsetY = 3;
   shadowBlur= 3;
+  defaultAspectRatios: array[0..12] of string =
+    ('1:1', '6:5', '5:4', '4:3', '11:8',
+     '1.414:1', '1.43:1', '3:2', '8:5',
+     '1.618:1', '5:3', '16:9', '2:1');
 
 type
   TLastEnteredValue = (valWidth,valHeight,valRatio);
@@ -73,6 +77,7 @@ type
     procedure ThemeChanged(Sender: TObject);
     procedure UpdatePreview;
     function GetBitDepth: integer;
+    procedure FillAspectRatios;
   public
     ForIcon: boolean;
     newImageResult: TBGRABitmap;
@@ -184,8 +189,6 @@ end;
 
 procedure TFNewImage.ToolButton_RotateClick(Sender: TObject);
 var tx,ty: integer;
-  s: string;
-  idxCol: integer;
 begin
   if FRecomputing then exit;
   FRecomputing:= true;
@@ -196,13 +199,7 @@ begin
   if FRatio <> 0 then
   begin
     FRatio := 1/FRatio;
-    s := ComboBox_Ratio.Text;
-    idxCol := pos(':',s);
-    if idxCol <> 0 then
-    begin
-      s := copy(s,idxCol+1,length(s)-idxCol)+':'+ copy(s,1,idxCol-1);
-      ComboBox_Ratio.Text := s;
-    end;
+    ComboBox_Ratio.Text := InverseRatio(ComboBox_Ratio.Text);
   end;
   FRecomputing:= false;
   if FLastEnteredValue = valWidth then
@@ -210,6 +207,7 @@ begin
   if FLastEnteredValue = valHeight then
     FLastEnteredValue:= valWidth;
   UpdatePreview;
+  FillAspectRatios;
 end;
 
 procedure TFNewImage.ComboBox_RatioChange(Sender: TObject);
@@ -268,11 +266,12 @@ begin
   end;
   FRecomputing:= false;
   UpdatePreview;
+  FillAspectRatios;
 end;
 
 procedure TFNewImage.ToolButton_ClearRatioClick(Sender: TObject);
 begin
-  ComboBox_Ratio.ItemIndex:= 0;
+  ComboBox_Ratio.Text := '';
   ComboBox_RatioChange(ComboBox_Ratio);
 end;
 
@@ -293,6 +292,10 @@ begin
 end;
 
 procedure TFNewImage.FormShow(Sender: TObject);
+var
+  currentRatio: single;
+  currentRatioStr: String;
+  currentRatioIdx, i: Integer;
 begin
   ToolBar_Rotate.Images := LazPaintInstance.Icons[DoScaleY(16,OriginalDPI)];
   ToolBar_Ratio.Images := ToolBar_Rotate.Images;
@@ -322,11 +325,34 @@ begin
     ComboBox_BitDepth.Visible := false;
     ComboBox_BitDepth.Text := '32';
   end;
-  if SpinEdit_Width.Value = SpinEdit_Height.Value then
+  FillAspectRatios;
+  FRatio := 0;
+  if SpinEdit_Height.Value <> 0 then
   begin
-    ComboBox_Ratio.Text := '1:1';
-    FRatio := ComputeRatio(ComboBox_Ratio.Text);
-    FLastEnteredValue := valRatio;
+    currentRatio := SpinEdit_Width.Value/SpinEdit_Height.Value;
+    currentRatioStr := RatioToStr(currentRatio);
+    currentRatioIdx := ComboBox_Ratio.Items.IndexOf(currentRatioStr);
+    if currentRatioIdx <> -1 then
+    begin
+      ComboBox_Ratio.Text := currentRatioStr;
+      FRatio := currentRatio;
+      FLastEnteredValue := valRatio;
+    end else
+    begin
+      for i := 0 to ComboBox_Ratio.Items.Count-1 do
+      begin
+        currentRatioStr := ComboBox_Ratio.Items[i];
+        currentRatio := ComputeRatio(currentRatioStr);
+        if (SpinEdit_Width.Value = round(SpinEdit_Height.Value*currentRatio)) or
+          (SpinEdit_Height.Value = round(SpinEdit_Width.Value/currentRatio)) then
+        begin
+          ComboBox_Ratio.Text := currentRatioStr;
+          FRatio := currentRatio;
+          FLastEnteredValue := valRatio;
+          break;
+        end;
+      end;
+    end;
   end;
   FRecomputing := false;
 
@@ -350,6 +376,7 @@ begin
   end;
   FRecomputing:= false;
   UpdatePreview;
+  FillAspectRatios;
 end;
 
 procedure TFNewImage.UpdatePreview;
@@ -381,6 +408,21 @@ begin
   result := StrToInt(ComboBox_BitDepth.Text);
 end;
 
+procedure TFNewImage.FillAspectRatios;
+var
+  aspect, rotatedAspect: String;
+begin
+  ComboBox_Ratio.Items.Clear;
+  for aspect in defaultAspectRatios do
+  begin
+    if SpinEdit_Width.Value >= SpinEdit_Height.Value then
+      rotatedAspect := aspect
+    else
+      rotatedAspect := InverseRatio(aspect);
+    ComboBox_Ratio.Items.add(rotatedAspect);
+  end;
+end;
+
 destructor TFNewImage.Destroy;
 begin
   if Assigned(FLazPaintInstance) then

lazpaint/ugraph.pas

@@ -16,6 +16,7 @@ var
 
 function ComputeRatio(ARatio: string): single;
 function RatioToStr(ARatio: single): string;
+function InverseRatio(ARatio: string): string;
 
 function RectUnion(const rect1,Rect2: TRect): TRect;
 function RectInter(const rect1,Rect2: TRect): TRect;
@@ -104,7 +105,8 @@ var
     inc(num, AValue*denom);
   end;
 
-const MaxDev = 3;
+const MaxDev = 6;
+  MaxDenom = 99;
 var
   dev: array[1..MaxDev] of integer;
   devCount, i: integer;
@@ -116,21 +118,43 @@ begin
   devCount := 0;
   repeat
     inc(devCount);
-    dev[devCount] := trunc(ARatio);
+    dev[devCount] := trunc(curVal);
     remain := frac(curVal);
     if abs(remain) < 1e-3 then break;
+    if devCount = MaxDev then
+    begin
+      if remain > 0.5 then inc(dev[devCount]);
+      break;
+    end;
     curVal := 1/remain;
-  until devCount = MaxDev;
-  num := dev[devCount];
-  denom := 1;
-  for i := devCount-1 downto 1 do
-  begin
-    InvFrac;
-    AddFrac(dev[i]);
-  end;
+  until false;
+  repeat
+    num := dev[devCount];
+    denom := 1;
+    for i := devCount-1 downto 1 do
+    begin
+      InvFrac;
+      AddFrac(dev[i]);
+    end;
+    if ((num >= denom) and (denom <= MaxDenom))
+       or ((num < denom) and (num <= MaxDenom))
+       or (devCount = 1) then break;
+    dec(devCount);
+  until false;
   result := IntToStr(num)+':'+IntToStr(denom);
 end;
 
+function InverseRatio(ARatio: string): string;
+var
+  elements: TStringArray;
+begin
+  elements := ARatio.Split([':']);
+  if length(elements) = 2 then
+    result := elements[1] + ':' + elements[0]
+  else
+    result := ARatio;
+end;
+
 function RectUnion(const rect1, Rect2: TRect): TRect;
 begin
   if IsRectEmpty(rect1) then