5 files changed, 205 insertions, 0 deletions
diff --git a/basegfx/Library_basegfx.mk b/basegfx/Library_basegfx.mk
index fa0607bff256..fc6a4794e695 100644
--- a/basegfx/Library_basegfx.mk
+++ b/basegfx/Library_basegfx.mk
@@ -66,6 +66,7 @@ $(eval $(call gb_Library_add_linked_libs,basegfx,\
 $(eval $(call gb_Library_add_exception_objects,basegfx,\
 	basegfx/source/tools/b2dclipstate \
 	basegfx/source/tools/canvastools \
+	basegfx/source/tools/zoomtools \
 	basegfx/source/tools/gradienttools \
 	basegfx/source/tools/keystoplerp \
 	basegfx/source/tools/liangbarsky \
diff --git a/basegfx/Package_inc.mk b/basegfx/Package_inc.mk
index 5767a8f8a954..13b5ff8bcc8c 100644
--- a/basegfx/Package_inc.mk
+++ b/basegfx/Package_inc.mk
@@ -37,6 +37,7 @@ $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tools/unopolypolygon.h
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tools/tools.hxx,basegfx/tools/tools.hxx))
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tools/unotools.hxx,basegfx/tools/unotools.hxx))
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tools/gradienttools.hxx,basegfx/tools/gradienttools.hxx))
+$(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tools/zoomtools.hxx,basegfx/tools/zoomtools.hxx))
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/numeric/ftools.hxx,basegfx/numeric/ftools.hxx))
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tuple/b3i64tuple.hxx,basegfx/tuple/b3i64tuple.hxx))
 $(eval $(call gb_Package_add_file,basegfx_inc,inc/basegfx/tuple/b3dtuple.hxx,basegfx/tuple/b3dtuple.hxx))
diff --git a/basegfx/StaticLibrary_basegfx_s.mk b/basegfx/StaticLibrary_basegfx_s.mk
index 79d6ed9373db..69616f74fd8e 100644
--- a/basegfx/StaticLibrary_basegfx_s.mk
+++ b/basegfx/StaticLibrary_basegfx_s.mk
@@ -72,6 +72,7 @@ $(WORKDIR)/CustomTarget/basegfx/source/%.cxx : $(SRCDIR)/basegfx/source/%.cxx
 $(eval $(call gb_StaticLibrary_add_generated_exception_objects,basegfx_s,\
 	CustomTarget/basegfx/source/tools/liangbarsky \
 	CustomTarget/basegfx/source/tools/canvastools \
+	CustomTarget/basegfx/source/tools/zoomtools \
 	CustomTarget/basegfx/source/tools/gradienttools \
 	CustomTarget/basegfx/source/tools/keystoplerp \
 	CustomTarget/basegfx/source/tools/unopolypolygon \
diff --git a/basegfx/inc/basegfx/tools/zoomtools.hxx b/basegfx/inc/basegfx/tools/zoomtools.hxx
new file mode 100644
index 000000000000..566418d3a8a8
--- /dev/null
+++ b/basegfx/inc/basegfx/tools/zoomtools.hxx
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * Version: MPL 1.1 / GPLv3+ / LGPLv3+
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License or as specified alternatively below. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * Major Contributor(s):
+ * Copyright (C) 2012 Tim Hardeck <thardeck@suse.com>
+ *
+ * All Rights Reserved.
+ *
+ * For minor contributions see the git repository.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 3 or later (the "GPLv3+"), or
+ * the GNU Lesser General Public License Version 3 or later (the "LGPLv3+"),
+ * in which case the provisions of the GPLv3+ or the LGPLv3+ are applicable
+ * instead of those above.
+ */
+
+#ifndef _BGFX_TOOLS_ZOOMTOOLS_HXX
+#define _BGFX_TOOLS_ZOOMTOOLS_HXX
+
+#include <sal/types.h>
+#include <basegfx/basegfxdllapi.h>
+
+//////////////////////////////////////////////////////////////////////////////
+
+namespace basegfx
+{
+    /** This namespace provides functions for optimized geometric zooming
+    */
+    namespace zoomtools
+    {
+        BASEGFX_DLLPUBLIC long zoomOut(long nCurrent);
+        BASEGFX_DLLPUBLIC long zoomIn(long nCurrent);
+        BASEGFX_DLLPUBLIC int zoomOut(int nCurrent);
+        BASEGFX_DLLPUBLIC int zoomIn(int nCurrent);
+    }
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/basegfx/source/tools/zoomtools.cxx b/basegfx/source/tools/zoomtools.cxx
new file mode 100644
index 000000000000..c6c8044c5953
--- /dev/null
+++ b/basegfx/source/tools/zoomtools.cxx
@@ -0,0 +1,150 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * Version: MPL 1.1 / GPLv3+ / LGPLv3+
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License or as specified alternatively below. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * Major Contributor(s):
+ * Copyright (C) 2012 Tim Hardeck <thardeck@suse.com>
+ *
+ * All Rights Reserved.
+ *
+ * For minor contributions see the git repository.
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 3 or later (the "GPLv3+"), or
+ * the GNU Lesser General Public License Version 3 or later (the "LGPLv3+"),
+ * in which case the provisions of the GPLv3+ or the LGPLv3+ are applicable
+ * instead of those above.
+ */
+
+#include <basegfx/tools/zoomtools.hxx>
+
+namespace basegfx
+{
+namespace zoomtools
+{
+
+/** 2^(1/4) as the default step
+
+    This ensures (unless the rounding is used) that 4 steps lead
+    to double / half zoom level.
+*/
+const double ZOOM_FACTOR = 1.1892071150027210667175;
+
+/**
+* Round a value against a specified multiple. Values below half
+* of the multiple are rounded down and all others are rounded up.
+*
+* @param nCurrent current value
+* @param nMultiple multiple against which the current value is rounded
+*/
+static long roundMultiple(long nCurrent, int nMultiple)
+{
+    // round zoom to a multiple of nMultiple
+    return (( nCurrent + nMultiple / 2 ) - ( nCurrent + nMultiple / 2 ) % nMultiple);
+}
+
+/**
+* Convert geometric progression results into more common values by
+* rounding them against certain multiples depending on the size.
+* Beginning with 50 the multiple is 5, with 100, 10, and so on.
+*
+* @param nCurrent current zoom factor
+*/
+static long roundZoom(double nCurrent)
+{
+    // convert nCurrent properly to int
+    long nNew = nCurrent + 0.5;
+
+    // round to more common numbers above 50
+    if (nNew > 1000) {
+        nNew = roundMultiple(nNew, 100);
+    } else if ( nNew > 500 ) {
+        nNew = roundMultiple(nNew, 50);
+    } else if ( nNew > 100 ) {
+        nNew = roundMultiple(nNew, 10);
+    } else if ( nNew > 50 ) {
+        nNew = roundMultiple(nNew, 5);
+    }
+
+    return nNew;
+}
+
+/**
+* Make sure that a certain step isn't skipped during the zooming
+* progress.
+*
+* @param nCurrent current zoom factor
+* @param nPrevious previous zoom factor
+* @param nStep step which shouldn't be skipped
+*/
+static long enforceStep(long nCurrent, long nPrevious, int nStep)
+{
+    if ((( nCurrent > nStep ) && ( nPrevious < nStep ))
+    || (( nCurrent < nStep ) && ( nPrevious > nStep )))
+        return nStep;
+    else
+        return nCurrent;
+}
+
+/**
+* Increasing the zoom level.
+*
+* @param nCurrent current zoom factor
+*/
+long zoomIn(long nCurrent)
+{
+    long nNew = roundZoom( nCurrent * ZOOM_FACTOR );
+    // make sure 100% isn't skipped
+    nNew = enforceStep(nNew, nCurrent, 100);
+    nNew = enforceStep(nNew, nCurrent, 25);
+    return nNew;
+}
+
+/**
+* Decreasing the zoom level.
+*
+* @param nCurrent current zoom factor
+*/
+long zoomOut(long nCurrent)
+{
+    long nNew = roundZoom( nCurrent / ZOOM_FACTOR );
+    // make sure 100% isn't skipped
+    nNew = enforceStep(nNew, nCurrent, 100);
+    nNew = enforceStep(nNew, nCurrent, 25);
+    return nNew;
+}
+
+/**
+* Increasing the zoom level.
+*
+* @param nCurrent current zoom factor
+*/
+int zoomIn(int nCurrent)
+{
+    return static_cast<int>( zoomIn( long( nCurrent ) ) );
+}
+
+/**
+* Decreasing the zoom level.
+*
+* @param nCurrent current zoom factor
+*/
+int zoomOut(int nCurrent)
+{
+    return static_cast<int>( zoomOut( long( nCurrent ) ) );
+}
+
+} // namespace zoomtools
+} // namespace basegfx
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */