From 15aa8e1f486e4e1d48adbfc0f0f5922bd478db29 Mon Sep 17 00:00:00 2001
From: Jaakko Keränen <jaakko.keranen@iki.fi>
Date: Wed, 10 Feb 2021 10:59:19 +0200
Subject: Window: Keep scroll position when resizing vertically

IssueID #138
---
 src/ui/documentwidget.c | 23 +++++++++++++++--------
 src/ui/window.c         | 10 +++++++++-
 src/ui/window.h         |  1 +
 3 files changed, 25 insertions(+), 9 deletions(-)

(limited to 'src')

diff --git a/src/ui/documentwidget.c b/src/ui/documentwidget.c
index 4063503f..b9aa551f 100644
--- a/src/ui/documentwidget.c
+++ b/src/ui/documentwidget.c
@@ -1533,18 +1533,25 @@ static const int homeRowKeys_[] = {
 static iBool handleCommand_DocumentWidget_(iDocumentWidget *d, const char *cmd) {
     iWidget *w = as_Widget(d);
     if (equal_Command(cmd, "window.resized") || equal_Command(cmd, "font.changed")) {
-        const iGmRun *mid = middleRun_DocumentWidget_(d);
-        const char *midLoc = (mid ? mid->text.start : NULL);
+        const iBool isHorizontalOnly =
+            argLabel_Command(cmd, "horiz") != 0 && !argLabel_Command(cmd, "vert");
         /* Alt/Option key may be involved in window size changes. */
         iChangeFlags(d->flags, showLinkNumbers_DocumentWidgetFlag, iFalse);
-        setWidth_GmDocument(d->doc, documentWidth_DocumentWidget_(d));
-        scroll_DocumentWidget_(d, 0);
-        if (midLoc) {
-            mid = findRunAtLoc_GmDocument(d->doc, midLoc);
-            if (mid) {
-                scrollTo_DocumentWidget_(d, mid_Rect(mid->bounds).y, iTrue);
+        if (isHorizontalOnly) {
+            const iGmRun *mid = middleRun_DocumentWidget_(d);
+            const char *midLoc = (mid ? mid->text.start : NULL);
+            setWidth_GmDocument(d->doc, documentWidth_DocumentWidget_(d));
+            scroll_DocumentWidget_(d, 0);
+            if (midLoc) {
+                mid = findRunAtLoc_GmDocument(d->doc, midLoc);
+                if (mid) {
+                    scrollTo_DocumentWidget_(d, mid_Rect(mid->bounds).y, iTrue);
+                }
             }
         }
+        else {
+            scroll_DocumentWidget_(d, 0); /* prevent overscroll */
+        }
         updateSideIconBuf_DocumentWidget_(d);
         updateOutline_DocumentWidget_(d);
         invalidate_DocumentWidget_(d);
diff --git a/src/ui/window.c b/src/ui/window.c
index 5c7fcaab..f9e58acb 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -667,9 +667,16 @@ static void updateRootSize_Window_(iWindow *d, iBool notifyAlways) {
     const iInt2 oldSize = *size;
     SDL_GetRendererOutputSize(d->render, &size->x, &size->y);
     if (notifyAlways || !isEqual_I2(oldSize, *size)) {
+        const iBool isHoriz = (d->lastNotifiedSize.x != size->x);
+        const iBool isVert  = (d->lastNotifiedSize.y != size->y);
         arrange_Widget(d->root);
-        postCommandf_App("window.resized width:%d height:%d", size->x, size->y);
+        postCommandf_App("window.resized width:%d height:%d horiz:%d vert:%d",
+                         size->x,
+                         size->y,
+                         isHoriz,
+                         isVert);
         postRefresh_App();
+        d->lastNotifiedSize = *size;
     }
 }
 
@@ -719,6 +726,7 @@ void init_Window(iWindow *d, iRect rect) {
     iZap(d->cursors);
     d->initialPos = rect.pos;
     d->lastRect = rect;
+    d->lastNotifiedSize = zero_I2();
     d->pendingCursor = NULL;
     d->isDrawFrozen = iTrue;
     d->isMouseInside = iTrue;
diff --git a/src/ui/window.h b/src/ui/window.h
index 8cadad1b..9e3f16bc 100644
--- a/src/ui/window.h
+++ b/src/ui/window.h
@@ -36,6 +36,7 @@ struct Impl_Window {
     SDL_Window *  win;
     iInt2         initialPos;
     iRect         lastRect; /* updated when window is moved/resized */
+    iInt2         lastNotifiedSize; /* keep track of horizontal/vertical notifications */
     iBool         isDrawFrozen; /* avoids premature draws while restoring window state */
     iBool         isMouseInside;
     uint32_t      focusGainedAt;
-- 
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