DocumentWidget: Line width based on font glyph width

The idea is that the amount of content should be the same per line regardless of the font.

5 files changed, 31 insertions, 16 deletions

diff --git a/src/ui/command.h b/src/ui/command.h
index 8dbaafad..8dcae892 100644
--- a/src/ui/command.h
+++ b/src/ui/command.h
@@ -23,6 +23,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
 #pragma once
 
 #include <the_Foundation/range.h>
+#include <the_Foundation/string.h>
 #include <the_Foundation/vec2.h>
 
 iBool       equal_Command           (const char *commandWithArgs, const char *command);
@@ -45,3 +46,6 @@ iString *       suffix_Command      (const char *, const char *label); /* until
 iLocalDef iBool hasLabel_Command(const char *d, const char *label) {
     return suffixPtr_Command(d, label) != NULL;
 }
+iLocalDef const char *cstr_Command(const char *d, const char *label) {
+    return cstr_Rangecc(range_Command(d, label));
+}
diff --git a/src/ui/documentwidget.c b/src/ui/documentwidget.c
index b83490f9..2ba2fa12 100644
--- a/src/ui/documentwidget.c
+++ b/src/ui/documentwidget.c
@@ -496,7 +496,8 @@ static int documentWidth_DocumentWidget_(const iDocumentWidget *d) {
                                      -1.0f, 10.0f); /* adapt to width */
     //printf("%f\n", adjust); fflush(stdout);
     return iMini(iMax(minWidth, bounds.size.x - gap_UI * (d->pageMargin + adjust) * 2),
-                 fontSize_UI * prefs->lineWidth * prefs->zoomPercent / 100);
+                 fontSize_UI * emRatio_Text(paragraph_FontId) * /* dependent on avg. glyph width */
+                 prefs->lineWidth * prefs->zoomPercent / 100);
 }
 
 static iRect documentBounds_DocumentWidget_(const iDocumentWidget *d) {
diff --git a/src/ui/text.c b/src/ui/text.c
index 25c79e23..8adfa019 100644
--- a/src/ui/text.c
+++ b/src/ui/text.c
@@ -1882,6 +1882,11 @@ int lineHeight_Text(int fontId) {
     return font_Text_(fontId)->height;
 }
 
+float emRatio_Text(int fontId) {
+    const iFont *font = font_Text_(fontId);
+    return font->emAdvance / font->height;
+}
+
 iTextMetrics measureRange_Text(int fontId, iRangecc text) {
     if (isEmpty_Range(&text)) {
         return (iTextMetrics){ init_Rect(0, 0, 0, lineHeight_Text(fontId)), zero_I2() };
diff --git a/src/ui/text.h b/src/ui/text.h
index f76c8125..af69795a 100644
--- a/src/ui/text.h
+++ b/src/ui/text.h
@@ -148,6 +148,7 @@ void    setContentFontSize_Text (iText *, float fontSizeFactor); /* affects all
 void    resetFonts_Text         (iText *);
 
 int     lineHeight_Text         (int fontId);
+float   emRatio_Text            (int fontId); /* em advance to line height ratio */
 iRect   visualBounds_Text       (int fontId, iRangecc text);
 
 iDeclareType(TextMetrics)
diff --git a/src/ui/util.c b/src/ui/util.c
index a4411ea5..354b1467 100644
--- a/src/ui/util.c
+++ b/src/ui/util.c
@@ -2169,6 +2169,15 @@ iWidget *makePreferences_Widget(void) {
         { "${prefs.imagestyle.preformat}", 0, 0, format_CStr("imagestyle.set arg:%d", preformatColorized_ImageStyle) },
         { NULL }
     };
+    const iMenuItem lineWidthItems[] = {
+        { "button id:prefs.linewidth.50 text:\u20132",                 0, 0, "linewidth.set arg:50" },
+        { "button id:prefs.linewidth.58 text:\u20131",                 0, 0, "linewidth.set arg:58" },
+        { "button id:prefs.linewidth.66 label:prefs.linewidth.normal", 0, 0, "linewidth.set arg:66" },
+        { "button id:prefs.linewidth.76 text:+1",                      0, 0, "linewidth.set arg:76" },
+        { "button id:prefs.linewidth.86 text:+2",                      0, 0, "linewidth.set arg:86" },
+        { "button id:prefs.linewidth.1000 label:prefs.linewidth.fill", 0, 0, "linewidth.set arg:1000" },
+        { NULL }
+    };
     /* Create the Preferences UI. */
     if (isUsingPanelLayout_Mobile()) {
         const iMenuItem pinSplitItems[] = {
@@ -2206,15 +2215,6 @@ iWidget *makePreferences_Widget(void) {
             { "button id:prefs.boldlink.light" },
             { NULL }  
         };
-        const iMenuItem lineWidthItems[] = {
-            { "button id:prefs.linewidth.30 text:\u20132", 0, 0, "linewidth.set arg:30" },
-            { "button id:prefs.linewidth.34 text:\u20131", 0, 0, "linewidth.set arg:34" },
-            { "button id:prefs.linewidth.38 label:prefs.linewidth.normal", 0, 0, "linewidth.set arg:38" },
-            { "button id:prefs.linewidth.43 text:+1", 0, 0, "linewidth.set arg:43" },
-            { "button id:prefs.linewidth.48 text:+2", 0, 0, "linewidth.set arg:48" },
-            { "button id:prefs.linewidth.1000 label:prefs.linewidth.fill", 0, 0, "linewidth.set arg:1000" },
-            { NULL }              
-        };
         const iMenuItem quoteItems[] = {
             { "button id:prefs.quoteicon.1 label:prefs.quoteicon.icon", 0, 0, "quoteicon.set arg:1" },
             { "button id:prefs.quoteicon.0 label:prefs.quoteicon.line", 0, 0, "quoteicon.set arg:0" },
@@ -2541,12 +2541,16 @@ iWidget *makePreferences_Widget(void) {
         addChild_Widget(headings, iClob(makeHeading_Widget("${prefs.linewidth}")));
         iWidget *widths = new_Widget();
         /* Line widths. */ {
-            addRadioButton_(widths, "prefs.linewidth.30", "\u20132", "linewidth.set arg:30");
-            addRadioButton_(widths, "prefs.linewidth.34", "\u20131", "linewidth.set arg:34");
-            addRadioButton_(widths, "prefs.linewidth.38", "${prefs.linewidth.normal}", "linewidth.set arg:38");
-            addRadioButton_(widths, "prefs.linewidth.43", "+1", "linewidth.set arg:43");
-            addRadioButton_(widths, "prefs.linewidth.48", "+2", "linewidth.set arg:48");
-            addRadioButton_(widths, "prefs.linewidth.1000", "${prefs.linewidth.fill}", "linewidth.set arg:1000");
+            /* TODO: Make this a utility function to build radio buttons from items. */
+            for (size_t i = 0; lineWidthItems[i].label; i++) {
+                const iMenuItem *lw = &lineWidthItems[i];
+                addRadioButton_(widths,
+                                cstr_Command(lw->label, "id"),
+                                hasLabel_Command(lw->label, "label")
+                                    ? cstr_Lang(cstr_Command(lw->label, "label"))
+                                    : cstr_Command(lw->label, "text"),
+                                lw->command);
+            }
         }
         addChildFlags_Widget(values, iClob(widths), arrangeHorizontal_WidgetFlag | arrangeSize_WidgetFlag);
         addPrefsInputWithHeading_(headings, values, "prefs.linespacing", iClob(new_InputWidget(5)));