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kwin: fixing blur bug for move/resize events

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The old blur version wrongly marked a cache region as valid with the
reason that this region would never become visible. It didnt matter
because the only case that this region could become visible was a
movement of the window on top, which back then would have forced a
workspace repaint of that region and as such would have invalidated
the cache anyway. With the introduction of addLayerRepaint the
last point is no longer true and we have to track the valid cache
regions more carefully.
This commit is contained in:
Philipp Knechtges 2012-02-16 21:11:51 +01:00
parent cb5360c53d
commit 2bfcfeceb4
1 changed files with 45 additions and 10 deletions
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55
effects/blur/blur.cpp
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@ -281,8 +281,9 @@ void BlurEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int t
}
// in case this window has regions to be blurred
const QRegion blurArea = blurRegion(w).translated(w->pos());
const QRegion expandedBlur = expand(blurArea);
const QRect screen(0, 0, displayWidth(), displayHeight());
const QRegion blurArea = blurRegion(w).translated(w->pos()) & screen;
const QRegion expandedBlur = expand(blurArea) & screen;
if (m_shouldCache) {
// we are caching the horizontally blurred background texture
@ -290,8 +291,11 @@ void BlurEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int t
// if a window underneath the blurred area is damaged we have to
// update the cached texture
QRegion damagedCache;
if (windows.contains(w) && !windows.value(w).dropCache) {
damagedCache = expand(expandedBlur & m_damagedArea) & expandedBlur;
if (windows.contains(w) && !windows.value(w).dropCache &&
windows.value(w).windowPos == w->pos() &&
windows.value(w).blurredBackground.size() == expandedBlur.boundingRect().size()) {
damagedCache = (expand(expandedBlur & m_damagedArea) |
(windows.value(w).damagedRegion & data.paint)) & expandedBlur;
} else {
damagedCache = expandedBlur;
}
@ -303,6 +307,7 @@ void BlurEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int t
data.paint |= expand(damagedArea);
if (windows.contains(w)) {
// In case we already have a texture cache mark the dirty regions invalid.
windows[w].damagedRegion &= expandedBlur;
windows[w].damagedRegion |= damagedCache;
windows[w].dropCache = false;
}
@ -508,11 +513,9 @@ void BlurEffect::doCachedBlur(EffectWindow *w, const QRegion& region, const floa
windows.insert(w, bwi);
} else if (windows.value(w).blurredBackground.size() != r.size()) {
windows[w].blurredBackground = GLTexture(r.width(),r.height());
windows[w].damagedRegion = expanded;
windows[w].dropCache = false;
windows[w].windowPos = w->pos();
} else if (windows.value(w).windowPos != w->pos()) {
windows[w].damagedRegion = expanded;
windows[w].dropCache = false;
windows[w].windowPos = w->pos();
}
@ -533,10 +536,42 @@ void BlurEffect::doCachedBlur(EffectWindow *w, const QRegion& region, const floa
pushMatrix();
#endif
// We only update that part of the background texture that is visible and marked as dirty.
const QRegion updateBackground = windows.value(w).damagedRegion & region;
/**
* Which part of the background texture can be updated ?
*
* Well this is a rather difficult question. We kind of rely on the fact, that
* we need a bigger background region being painted before, more precisely if we want to
* blur region A we need the background region expand(A). This business logic is basically
* done in prePaintWindow:
* data.paint |= expand(damagedArea);
*
* Now "data.paint" gets clipped and becomes what we receive as the "region" variable
* in this function. In theory there is now only one function that does this clipping
* and this is paintSimpleScreen. The clipping has the effect that "damagedRegion"
* is no longer a subset of "region" and we cannot fully validate the cache within one
* rendering pass. If we would now update the "damageRegion & region" part of the cache
* we would wrongly update the part of the cache that is next to the "region" border and
* which lies within "damagedRegion", just because we cannot assume that the framebuffer
* outside of "region" is valid. Therefore the maximal damaged region of the cache that can
* be repainted is given by:
* validUpdate = damagedRegion - expand(damagedRegion - region);
*
* Now you may ask what is with the rest of "damagedRegion & region" that is not part
* of "validUpdate" but also might end up on the screen. Well under the assumption
* that only the occlusion culling can shrink "data.paint", we can control this by reducing
* the opaque area of every window by a margin of the blurring radius (c.f. prePaintWindow).
* This way we are sure that this area is overpainted by a higher opaque window.
*
* Apparently paintSimpleScreen is not the only function that can influence "region".
* In fact every effect's paintWindow that is called before Blur::paintWindow
* can do so (e.g. SlidingPopups). Hence we have to make the compromise that we update
* "damagedRegion & region" of the cache but only mark "validUpdate" as valid.
**/
const QRegion damagedRegion = windows.value(w).damagedRegion;
const QRegion updateBackground = damagedRegion & region;
const QRegion validUpdate = damagedRegion - expand(damagedRegion - region);
if (!updateBackground.isEmpty()) {
if (!validUpdate.isEmpty()) {
const QRect updateRect = (expand(updateBackground) & expanded).boundingRect();
// First we have to copy the background from the frontbuffer
// into a scratch texture (in this case "tex").
@ -573,7 +608,7 @@ void BlurEffect::doCachedBlur(EffectWindow *w, const QRegion& region, const floa
GLRenderTarget::popRenderTarget();
tex.unbind();
// mark the updated region as valid
windows[w].damagedRegion -= updateBackground;
windows[w].damagedRegion -= validUpdate;
}
// Now draw the horizontally blurred area back to the backbuffer, while