31640cce53
Change-Id: If33ae9acbc1ed17398584efa3574566b2d854b3e Reviewed-on: https://gerrit.libreoffice.org/c/core/+/140149 Tested-by: Jenkins Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
112 lines
4.8 KiB
C++
112 lines
4.8 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#pragma once
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#include <vcl/virdev.hxx>
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// Helper class *exclusively* for VclProcessor2D. It should only
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// be used internally, see current four usages. It is used to
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// render something with mask or transparence (see MaskPrimitive2D,
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// UnifiedTransparencePrimitive2D and TransparencePrimitive2D) or
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// as tooling for preparing pixelized output in the renderer
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// (see PatternFillPrimitive2D) if that is faster.
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//
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// To do so, initializing this instance takes over a lot of work
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// from you:
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// - It initializes a 'Content' VDev which is buffered (since it had
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// shown that re-allocating all the time is slower). It checks
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// visibility and all usages initializing this should check for
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// isVisible() after construction.
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// - It pre-initializes the 'Content' VDev with blitting the content
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// of the target VDev.
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// - It offers to get a 'Transparence' VDev (also from the buffer) if
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// needed.
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//
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// If 'Transparence' is/was used, it combines as needed to paint
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// all buffered stuff to target VDev when calling paint().
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// Caution: It is designed to use *either* a fixed transparence in
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// the paint()-call *or* a fill TransparenceChannel using a
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// 'Transparence' VDev. It is *not* designed to use/combine
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// both - it's simply not needed for it's intended purpose/usage.
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//
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// Painting transparent works based on a simple principle: It first
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// blits the original content of the target VDev. Then the content
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// is painted on top of that, plus a Transparence/Mask prepared.
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// The combination always works since unchanged pixels will not
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// change, independent of the transparence value [0..255] it gets
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// mixed with. Or the other way around: Only pixels changed on the
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// Content *can* be changed by transparence values.
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//
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// This is 2.5 times faster than first painting to a
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// 'combined' VDev that supports transparency, as is used by the
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// presentation engine.
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// For the mentioned factor refer to:
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// Patch to demonstrate former and now repaint differences
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// https://gerrit.libreoffice.org/c/core/+/129301
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// git fetch https://git.libreoffice.org/core refs/changes/01/129301/3 && git cherry-pick FETCH_HEAD
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//
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// Note: This principle only works when the target is RGB, so
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// useful for EditViews like for PrimitiveRenderers where this is
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// the case. For usage with GBA targets the starting conditions
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// would have to be modified to not blend against the initial color
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// of 'Content' (usually COL_WHITE).
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//
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// After having finished the rework of ShadowPrimitive2D,
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// SoftEdgePrimitive2D and GlowPrimitive2D (see commits:)
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// e735ad1c57cddaf17d6ffc0cf15b5e14fa63c4ad
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// 707b0c328a282d993fa33b618083d20b6c521de6
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// c2d1458723c66c2fd717a112f89f773226adc841
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// which used the impBufferDevice in such a mode combined with
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// mentioned 'combined' transparence VDev it is now possible
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// to return to this former, much faster method.
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//
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// Please do *not* hack/use this helper class, better create
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// a new one fitting your/the intended purpose. I do not want
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// to see losing performance by this getting modified again.
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//
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// Note: Using that 'combined' transparence VDev is not really
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// recommended, it may vanish anytime. That it works with
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// PrimitiveRenderers *at all* is neither designed nor tested
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// or recommended - it's pure coincidence.
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//
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// I hope that for the future all this will vanish by getting to
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// fully RGBA-capable devices - what is planned and makes sense.
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namespace drawinglayer
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{
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class impBufferDevice
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{
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OutputDevice& mrOutDev;
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VclPtr<VirtualDevice> mpContent;
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VclPtr<VirtualDevice> mpAlpha;
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tools::Rectangle maDestPixel;
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public:
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impBufferDevice(OutputDevice& rOutDev, const basegfx::B2DRange& rRange);
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~impBufferDevice();
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void paint(double fTrans = 0.0);
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bool isVisible() const { return !maDestPixel.IsEmpty(); }
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VirtualDevice& getContent();
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VirtualDevice& getTransparence();
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};
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} // end of namespace drawinglayer
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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