Add wrapping support to text measuring

This fixes #72

I also improved the default sizes of text-based
elements including button. This fixes #69

Ooui.Forms/Extensions/ElementExtensions.cs

@@ -14,7 +14,7 @@ namespace Ooui.Forms.Extensions
             var measured = false;
 
             if (self.Style.Width.Equals ("inherit")) {
-                s = self.Text.MeasureSize (self.Style);
+                s = self.Text.MeasureSize (self.Style, widthConstraint, heightConstraint);
                 measured = true;
                 rw = double.IsPositiveInfinity (s.Width) ? double.PositiveInfinity : Math.Ceiling (s.Width);
             }
@@ -24,7 +24,7 @@ namespace Ooui.Forms.Extensions
 
             if (self.Style.Height.Equals ("inherit")) {
                 if (!measured) {
-                    s = self.Text.MeasureSize (self.Style);
+                    s = self.Text.MeasureSize (self.Style, widthConstraint, heightConstraint);
                     measured = true;
                 }
                 rh = double.IsPositiveInfinity (s.Height) ? double.PositiveInfinity : Math.Ceiling (s.Height * 1.4);

Ooui.Forms/Extensions/FontExtensions.cs

@@ -38,36 +38,65 @@ namespace Ooui.Forms.Extensions
             }
         }
 
-        public static Size MeasureSize (this string text, string fontFamily, double fontSize, FontAttributes fontAttrs)
+        public static Size MeasureSize (this string text, string fontFamily, double fontSize, FontAttributes fontAttrs, double widthConstraint, double heightConstraint)
         {
             if (string.IsNullOrEmpty (text))
                 return Size.Zero;
 
             var fontHeight = fontSize;
+            var lineHeight = fontHeight * 1.4;
 
             var isBold = fontAttrs.HasFlag (FontAttributes.Bold);
 
             var props = isBold ? BoldCharacterProportions : CharacterProportions;
             var avgp = isBold ? BoldAverageCharProportion : AverageCharProportion;
 
-            var pwidth = 1.0e-6; // Tiny little padding to account for sampling errors
+            var px = 0.0;
-            for (var i = 0; i < text.Length; i++) {
+            var lines = 1;
+            var maxPWidth = 0.0;
+            var pwidthConstraint = double.IsPositiveInfinity (widthConstraint) ? double.PositiveInfinity : widthConstraint / fontSize;
+            var lastSpaceWidth = -1.0;
+
+            // Tiny little padding to account for sampling errors
+            var pwidthHack = 1.0e-6;
+            var plineHack = 0.333;
+
+            var n = text != null ? text.Length : 0;
+
+            for (var i = 0; i < n; i++) {
                 var c = (int)text[i];
-                if (c < 128) {
+                var pw = (c < 128) ? props[c] : avgp;
-                    pwidth += props[c];
+                // Should we wrap?
+                if (px + pw + plineHack > pwidthConstraint) {
+                    lines++;
+                    if (lastSpaceWidth > 0) {
+                        maxPWidth = Math.Max (maxPWidth, lastSpaceWidth + pwidthHack);
+                        px = pw - lastSpaceWidth;
+                        lastSpaceWidth = -1;
                     }
                     else {
-                    pwidth += avgp;
+                        maxPWidth = Math.Max (maxPWidth, px + pwidthHack);
+                        px = 0;
                     }
                 }
-            var width = fontSize * pwidth;
+                if (c == ' ') {
+                    lastSpaceWidth = pw;
+                }
+                px += pw;
+            }
+            maxPWidth = Math.Max (maxPWidth, px + pwidthHack);
+            var width = fontSize * maxPWidth;
+            var height = lines * lineHeight;
 
-            return new Size (width, fontHeight);
+            // Console.WriteLine ($"MEASURE TEXT SIZE {widthConstraint}x{heightConstraint} \"{text}\" == {width}x{height}");
+
+            return new Size (width, height);
         }
 
-        public static Size MeasureSize (this string text, Style style)
+        public static Size MeasureSize (this string text, Style style, double widthConstraint, double heightConstraint)
         {
-            return MeasureSize (text, "", 14, FontAttributes.None);
+            // System.Console.WriteLine("!!! MEASURE STYLED TEXT SIZE: " + style);
+            return MeasureSize (text, "", 14, FontAttributes.None, widthConstraint, heightConstraint);
         }
 
         public static string ToOouiTextAlign (this TextAlignment align)

Ooui.Forms/Renderers/ButtonRenderer.cs

@@ -14,8 +14,8 @@ namespace Ooui.Forms.Renderers
 
         public override SizeRequest GetDesiredSize (double widthConstraint, double heightConstraint)
         {
-            var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes);
+            var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
-            size = new Size (size.Width, size.Height * 1.428 + 14);
+            size = new Size (size.Width + 2 * Element.FontSize, size.Height + Element.FontSize);
             return new SizeRequest (size, size);
         }
 

Ooui.Forms/Renderers/DatePickerRenderer.cs

@@ -13,8 +13,8 @@ namespace Ooui.Forms.Renderers
 
         public override SizeRequest GetDesiredSize (double widthConstraint, double heightConstraint)
         {
-            var size = "00/00/0000".MeasureSize ("", 16.0, FontAttributes.None);
+            var size = "00/00/0000".MeasureSize ("", 16.0, FontAttributes.None, widthConstraint, heightConstraint);
-            size = new Size (size.Width, size.Height * 1.428 + 14);
+            size = new Size (size.Width, size.Height);
             return new SizeRequest (size, size);
         }
 

Ooui.Forms/Renderers/EntryRenderer.cs

@@ -21,14 +21,12 @@ namespace Ooui.Forms.Renderers
             if (text == null || text.Length == 0) {
                 text = Element.Placeholder;
             }
-            Size size;
             if (text == null || text.Length == 0) {
-                size = new Size (Element.FontSize * 0.25, Element.FontSize);
+                text = " ";
             }
-            else {
+            var size = text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
-                size = text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes);
+            var vpadding = Element.FontSize;
-            }
+            size = new Size (size.Width, size.Height + vpadding);
-            size = new Size (size.Width, size.Height * 1.428 + 14);
             return new SizeRequest (size, size);
         }
 
@@ -149,7 +147,7 @@ namespace Ooui.Forms.Renderers
         {
             if (initialSize == Size.Zero) {
                 var testString = "Tj";
-                initialSize = testString.MeasureSize (Control.Style);
+                initialSize = testString.MeasureSize (Control.Style, double.PositiveInfinity, double.PositiveInfinity);
             }
 
             Element.SetStyleFont (Element.FontFamily, Element.FontSize, Element.FontAttributes, Control.Style);

Ooui.Forms/Renderers/LabelRenderer.cs

@@ -16,11 +16,12 @@ namespace Ooui.Forms.Renderers
 
         public override SizeRequest GetDesiredSize (double widthConstraint, double heightConstraint)
         {
+            // System.Console.WriteLine($"Label.GetDesiredSize ({widthConstraint}, {heightConstraint})");
             if (!_perfectSizeValid) {
-                var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes);
+                var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, double.PositiveInfinity, double.PositiveInfinity);
                 size.Width = Math.Ceiling (size.Width);
-                size.Height = Math.Ceiling (size.Height * 1.4);
+                size.Height = Math.Ceiling (size.Height);
-                _perfectSize = new SizeRequest (size, size);
+                _perfectSize = new SizeRequest (size, new Size (Element.FontSize, Element.FontSize));
                 _perfectSizeValid = true;
             }
 
@@ -30,7 +31,8 @@ namespace Ooui.Forms.Renderers
             if (widthFits && heightFits)
                 return _perfectSize;
 
-            var result = base.GetDesiredSize (widthConstraint, heightConstraint);
+            var resultRequestSize = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
+            var result = new SizeRequest (resultRequestSize, resultRequestSize);
             var tinyWidth = Math.Min (10, result.Request.Width);
             result.Minimum = new Size (tinyWidth, result.Request.Height);
 

Ooui.Forms/Renderers/LinkLabelRenderer.cs

@@ -14,10 +14,10 @@ namespace Ooui.Forms.Renderers
         public override SizeRequest GetDesiredSize (double widthConstraint, double heightConstraint)
         {
             if (!_perfectSizeValid) {
-                var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes);
+                var size = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, double.PositiveInfinity, double.PositiveInfinity);
                 size.Width = Math.Ceiling (size.Width);
-                size.Height = Math.Ceiling (size.Height * 1.4);
+                size.Height = Math.Ceiling (size.Height);
-                _perfectSize = new SizeRequest (size, size);
+                _perfectSize = new SizeRequest (size, new Size (Element.FontSize, Element.FontSize));
                 _perfectSizeValid = true;
             }
 
@@ -27,7 +27,8 @@ namespace Ooui.Forms.Renderers
             if (widthFits && heightFits)
                 return _perfectSize;
 
-            var result = base.GetDesiredSize (widthConstraint, heightConstraint);
+            var resultRequestSize = Element.Text.MeasureSize (Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
+            var result = new SizeRequest (resultRequestSize, resultRequestSize);
             var tinyWidth = Math.Min (10, result.Request.Width);
             result.Minimum = new Size (tinyWidth, result.Request.Height);
 

Ooui.Forms/Renderers/SearchBarRenderer.cs

@@ -27,9 +27,9 @@ namespace Ooui.Forms.Renderers
             }
             else
             {
-                size = text.MeasureSize(Element.FontFamily, Element.FontSize, Element.FontAttributes);
+                size = text.MeasureSize(Element.FontFamily, Element.FontSize, Element.FontAttributes, widthConstraint, heightConstraint);
             }
-            size = new Size(size.Width, size.Height * 1.428 + 14);
+            size = new Size(size.Width, size.Height + Element.FontSize);
             return new SizeRequest(size, size);
         }
 

Ooui.Forms/Renderers/TimePickerRenderer.cs

@@ -13,8 +13,9 @@ namespace Ooui.Forms.Renderers
 
         public override SizeRequest GetDesiredSize(double widthConstraint, double heightConstraint)
         {
-            var size = "00:00:00".MeasureSize(string.Empty, 16.0, FontAttributes.None);
+            var fontSize = 16.0;
-            size = new Size(size.Width, size.Height * 1.428 + 14);
+            var size = "00:00:00".MeasureSize(string.Empty, fontSize, FontAttributes.None, widthConstraint, heightConstraint);
+            size = new Size(size.Width, size.Height + fontSize);
             return new SizeRequest(size, size);
         }
 

Samples/WrappingTextSample.cs

@@ -0,0 +1,43 @@
+using System;
+using Xamarin.Forms;
+
+namespace Samples
+{
+    public class WrappingTextSample : ISample
+    {
+        public string Title => "Xamarin.Forms Wrapping Text";
+
+        public Ooui.Element CreateElement()
+        {
+            var rows = new StackLayout { Orientation = StackOrientation.Vertical };
+
+            var row0 = new StackLayout { Orientation = StackOrientation.Horizontal, BackgroundColor = Color.Azure };
+            row0.Children.Add (new Label { Text = shortText, LineBreakMode = LineBreakMode.WordWrap });
+            row0.Children.Add (new Label { Text = mediumText, LineBreakMode = LineBreakMode.WordWrap });
+            row0.Children.Add (new Label { Text = longText, LineBreakMode = LineBreakMode.WordWrap });
+            rows.Children.Add (row0);
+
+            var row1 = new StackLayout { Orientation = StackOrientation.Horizontal, BackgroundColor = Color.GhostWhite };
+            row1.Children.Add (new Label { Text = shortText, FontAttributes = FontAttributes.Bold, HorizontalOptions = LayoutOptions.Start });
+            row1.Children.Add (new Label { Text = mediumText, FontAttributes = FontAttributes.Bold, HorizontalOptions = LayoutOptions.FillAndExpand });
+            row1.Children.Add (new Label { Text = longText, FontAttributes = FontAttributes.Bold, HorizontalOptions = LayoutOptions.End });
+            rows.Children.Add (row1);
+
+            var page = new ContentPage
+            {
+                Content = rows
+            };
+
+            return page.GetOouiElement();
+        }
+
+        public void Publish()
+        {
+            Ooui.UI.Publish("/wrapping", CreateElement);
+        }
+
+        const string shortText = "Lorem ipsum dolor sit amet.";
+        const string mediumText = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.";
+        const string longText = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
+    }
+}