gui: proportional scrollbars
- Attribute "recth" in the <fastscroll> element is now the
*minimum* height for the scrollbar.
- Dragging the scrollbar moves the list.
- Touching outside the scrollbar jumps to the relative position.
Change-Id: Ic1f20b5ec68cf49e5be56be34f0c58c0f474618b
diff --git a/gui/scrolllist.cpp b/gui/scrolllist.cpp
index 4b772d4..70a54e5 100644
--- a/gui/scrolllist.cpp
+++ b/gui/scrolllist.cpp
@@ -44,6 +44,7 @@
mFont = NULL;
mBackgroundW = mBackgroundH = 0;
mFastScrollW = mFastScrollLineW = mFastScrollRectW = mFastScrollRectH = 0;
+ mFastScrollRectCurrentY = mFastScrollRectCurrentH = mFastScrollRectTouchY = 0;
lastY = last2Y = fastScroll = 0;
mUpdate = 0;
touchDebounce = 6;
@@ -284,7 +285,7 @@
yPos += actualItemHeight;
}
- // Render the Header (last so that it overwrites the top most row for per pixel scrolling)
+ // Render the Header
yPos = mRenderY;
if (mHeaderH > 0) {
// First step, fill background
@@ -310,35 +311,41 @@
gr_fill(mRenderX, yPos + mHeaderH - mHeaderSeparatorH, mRenderW, mHeaderSeparatorH);
}
- // render fast scroll
- lines = GetDisplayItemCount();
- if (hasScroll) {
- int startX = listW + mRenderX;
- int fWidth = mRenderW - listW;
- int fHeight = mRenderH - mHeaderH;
-
- // line
- gr_color(mFastScrollLineColor.red, mFastScrollLineColor.green, mFastScrollLineColor.blue, mFastScrollLineColor.alpha);
- gr_fill(startX + fWidth/2, mRenderY + mHeaderH, mFastScrollLineW, mRenderH - mHeaderH);
-
- // rect
- int pct = 0;
- if (GetDisplayRemainder() != 0) {
- // Properly handle the percentage if a partial line is present
- int partial_line_size = actualItemHeight - GetDisplayRemainder();
- pct = ((firstDisplayedItem*actualItemHeight - y_offset)*100)/(listSize*actualItemHeight-((lines + 1)*actualItemHeight) + partial_line_size);
- } else {
- pct = ((firstDisplayedItem*actualItemHeight - y_offset)*100)/(listSize*actualItemHeight-lines*actualItemHeight);
- }
- int mFastScrollRectX = startX + (fWidth - mFastScrollRectW)/2;
- int mFastScrollRectY = mRenderY+mHeaderH + ((fHeight - mFastScrollRectH)*pct)/100;
-
- gr_color(mFastScrollRectColor.red, mFastScrollRectColor.green, mFastScrollRectColor.blue, mFastScrollRectColor.alpha);
- gr_fill(mFastScrollRectX, mFastScrollRectY, mFastScrollRectW, mFastScrollRectH);
- }
- mUpdate = 0;
// reset clipping
gr_noclip();
+
+ // render fast scroll
+ if (hasScroll) {
+ int fWidth = mRenderW - listW;
+ int fHeight = mRenderH - mHeaderH;
+ int centerX = listW + mRenderX + fWidth / 2;
+
+ // first determine the total list height and where we are in the list
+ int totalHeight = GetItemCount() * actualItemHeight; // total height of the full list in pixels
+ int topPos = firstDisplayedItem * actualItemHeight - y_offset;
+
+ // now scale it proportionally to the scrollbar height
+ int boxH = fHeight * fHeight / totalHeight; // proportional height of the displayed portion
+ boxH = std::max(boxH, mFastScrollRectH); // but keep a minimum height
+ int boxY = (fHeight - boxH) * topPos / (totalHeight - fHeight); // pixels relative to top of list
+ int boxW = mFastScrollRectW;
+
+ int x = centerX - boxW / 2;
+ int y = mRenderY + mHeaderH + boxY;
+
+ // line above and below box (needs to be split because box can be transparent)
+ gr_color(mFastScrollLineColor.red, mFastScrollLineColor.green, mFastScrollLineColor.blue, mFastScrollLineColor.alpha);
+ gr_fill(centerX - mFastScrollLineW / 2, mRenderY + mHeaderH, mFastScrollLineW, boxY);
+ gr_fill(centerX - mFastScrollLineW / 2, y + boxH, mFastScrollLineW, fHeight - boxY - boxH);
+
+ // box
+ gr_color(mFastScrollRectColor.red, mFastScrollRectColor.green, mFastScrollRectColor.blue, mFastScrollRectColor.alpha);
+ gr_fill(x, y, boxW, boxH);
+
+ mFastScrollRectCurrentY = boxY;
+ mFastScrollRectCurrentH = boxH;
+ }
+ mUpdate = 0;
return 0;
}
@@ -416,8 +423,20 @@
switch (state)
{
case TOUCH_START:
- if (hasScroll && x >= mRenderX + mRenderW - mFastScrollW)
+ if (hasScroll && x >= mRenderX + mRenderW - mFastScrollW) {
fastScroll = 1; // Initial touch is in the fast scroll region
+ int fastScrollBoxTop = mFastScrollRectCurrentY + mRenderY + mHeaderH;
+ int fastScrollBoxBottom = fastScrollBoxTop + mFastScrollRectCurrentH;
+ if (y >= fastScrollBoxTop && y < fastScrollBoxBottom)
+ // user grabbed the fastscroll bar
+ // try to keep the initially touched part of the scrollbar under the finger
+ mFastScrollRectTouchY = y - fastScrollBoxTop;
+ else
+ // user tapped outside the fastscroll bar
+ // center fastscroll rect on the initial touch position
+ mFastScrollRectTouchY = mFastScrollRectCurrentH / 2;
+ }
+
if (scrollingSpeed != 0) {
selectedItem = NO_ITEM; // this allows the user to tap the list to stop the scrolling without selecting the item they tap
scrollingSpeed = 0; // stop scrolling on a new touch
@@ -433,36 +452,20 @@
case TOUCH_DRAG:
if (fastScroll)
{
- int pct = ((y-mRenderY-mHeaderH)*100)/(mRenderH-mHeaderH);
- int totalSize = GetItemCount();
- int lines = GetDisplayItemCount();
+ int relY = y - mRenderY - mHeaderH; // touch position relative to window
+ int windowH = mRenderH - mHeaderH;
+ int totalHeight = GetItemCount() * actualItemHeight; // total height of the full list in pixels
- float l = float((totalSize-lines)*pct)/100;
- if(l + lines >= totalSize)
- {
- firstDisplayedItem = totalSize - lines;
- if (GetDisplayRemainder() != 0) {
- // There's a partial row displayed, set the scrolling offset so that the last item really is at the very bottom
- firstDisplayedItem--;
- y_offset = GetDisplayRemainder() - actualItemHeight;
- } else {
- // There's no partial row so zero out the offset
- y_offset = 0;
- }
- }
- else
- {
- if (l < 0)
- l = 0;
- firstDisplayedItem = l;
- y_offset = -(l - int(l))*actualItemHeight;
- if (GetDisplayRemainder() != 0) {
- // There's a partial row displayed, make sure y_offset doesn't go past the max
- if (firstDisplayedItem == totalSize - lines - 1 && y_offset < GetDisplayRemainder() - actualItemHeight)
- y_offset = GetDisplayRemainder() - actualItemHeight;
- } else if (firstDisplayedItem == totalSize - lines)
- y_offset = 0;
- }
+ // calculate new top position of the fastscroll bar relative to window
+ int newY = relY - mFastScrollRectTouchY;
+ // keep it fully inside the list
+ newY = std::min(std::max(newY, 0), windowH - mFastScrollRectCurrentH);
+
+ // now compute the new scroll position for the list
+ int newTopPos = newY * (totalHeight - windowH) / (windowH - mFastScrollRectCurrentH); // new top pixel of list
+ newTopPos = std::min(newTopPos, totalHeight - windowH); // account for rounding errors
+ firstDisplayedItem = newTopPos / actualItemHeight;
+ y_offset = - newTopPos % actualItemHeight;
selectedItem = NO_ITEM;
mUpdate = 1;
@@ -490,6 +493,8 @@
break;
case TOUCH_RELEASE:
+ if (fastScroll)
+ mUpdate = 1; // get rid of touch effects on the fastscroll bar
fastScroll = 0;
if (selectedItem != NO_ITEM) {
// We've selected an item!