MathUtils: Add tangential interpolation

Reuse it in TaskProgress and in ProgressTimer.
Rename MathUtils::interpolate() into interpolateLinear()

Change-Id: Iff4cda1e3b8782cd26277ec75046ca5526be92c0
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

11 files changed, 124 insertions, 23 deletions

diff --git a/src/libs/utils/mathutils.cpp b/src/libs/utils/mathutils.cpp
index 465d4d5f99..d9e18b18a3 100644
--- a/src/libs/utils/mathutils.cpp
+++ b/src/libs/utils/mathutils.cpp
@@ -12,7 +12,7 @@ namespace Utils::MathUtils {
     For x = x1 it returns y1.
     For x = x2 it returns y2.
 */
-int interpolate(int x, int x1, int x2, int y1, int y2)
+int interpolateLinear(int x, int x1, int x2, int y1, int y2)
 {
     if (x1 == x2)
         return y1; // or the middle point between y1 and y2?
@@ -27,4 +27,21 @@ int interpolate(int x, int x1, int x2, int y1, int y2)
     return qRound((double)numerator / denominator);
 }
 
+/*!
+    Tangential interpolation:
+    For x = 0 it returns y1.
+    For x = xHalfLife it returns 50 % of the distance between y1 and y2.
+    For x = infinity it returns y2.
+*/
+int interpolateTangential(int x, int xHalfLife, int y1, int y2)
+{
+    if (x == 0)
+        return y1;
+    if (y1 == y2)
+        return y1;
+    const double mapped = atan2(double(x), double(xHalfLife));
+    const double progress = y1 + (y2 - y1) * mapped * 2 / M_PI;
+    return qRound(progress);
+}
+
 } // namespace Utils::Math
diff --git a/src/libs/utils/mathutils.h b/src/libs/utils/mathutils.h
index 20ae6cd342..8a9af9e4e6 100644
--- a/src/libs/utils/mathutils.h
+++ b/src/libs/utils/mathutils.h
@@ -7,6 +7,7 @@
 
 namespace Utils::MathUtils {
 
-QTCREATOR_UTILS_EXPORT int interpolate(int x, int x1, int x2, int y1, int y2);
+QTCREATOR_UTILS_EXPORT int interpolateLinear(int x, int x1, int x2, int y1, int y2);
+QTCREATOR_UTILS_EXPORT int interpolateTangential(int x, int xHalfLife, int y1, int y2);
 
 } // namespace Utils::Math
diff --git a/src/plugins/coreplugin/progressmanager/progressmanager.cpp b/src/plugins/coreplugin/progressmanager/progressmanager.cpp
index 9891a2b3f4..1b4166df5a 100644
--- a/src/plugins/coreplugin/progressmanager/progressmanager.cpp
+++ b/src/plugins/coreplugin/progressmanager/progressmanager.cpp
@@ -13,6 +13,7 @@
 
 #include <extensionsystem/pluginmanager.h>
 #include <utils/hostosinfo.h>
+#include <utils/mathutils.h>
 #include <utils/qtcassert.h>
 #include <utils/stylehelper.h>
 #include <utils/theme/theme.h>
@@ -27,7 +28,6 @@
 #include <QStyle>
 #include <QStyleOption>
 #include <QTimer>
-#include <QtMath>
 #include <QVariant>
 
 static const char kSettingsGroup[] = "Progress";
@@ -779,13 +779,8 @@ ProgressTimer::ProgressTimer(const QFutureInterfaceBase &futureInterface,
 void ProgressTimer::handleTimeout()
 {
     ++m_currentTime;
-
-    // This maps expectation to atan(1) to Pi/4 ~= 0.78, i.e. snaps
-    // from 78% to 100% when expectations are met at the time the
-    // future finishes. That's not bad for a random choice.
-    const double mapped = atan2(double(m_currentTime) * TimerInterval / 1000.0,
-                                double(m_expectedTime));
-    const double progress = 100 * 2 * mapped / M_PI;
-    m_futureInterface.setProgressValue(int(progress));
+    const int halfLife = qRound(1000.0 * m_expectedTime / TimerInterval);
+    const int progress = MathUtils::interpolateTangential(m_currentTime, halfLife, 0, 100);
+    m_futureInterface.setProgressValue(progress);
 }
 
diff --git a/src/plugins/coreplugin/progressmanager/taskprogress.cpp b/src/plugins/coreplugin/progressmanager/taskprogress.cpp
index 13ad40b7fa..ba0000a115 100644
--- a/src/plugins/coreplugin/progressmanager/taskprogress.cpp
+++ b/src/plugins/coreplugin/progressmanager/taskprogress.cpp
@@ -6,12 +6,12 @@
 #include "futureprogress.h"
 #include "progressmanager.h"
 
+#include <utils/mathutils.h>
 #include <utils/qtcassert.h>
 #include <utils/tasktree.h>
 
 #include <QFutureWatcher>
 #include <QTimer>
-#include <QtMath>
 
 using namespace Utils;
 
@@ -80,13 +80,11 @@ void TaskProgressPrivate::advanceProgress(int newValue)
 
 void TaskProgressPrivate::updateProgress()
 {
-    // This maps expectation to atan(1) to Pi/4 ~= 0.78, i.e. snaps
-    // from 78% to 100% when expectations are met at the time the
-    // future finishes. That's not bad for a random choice.
-    const double mapped = atan2(double(m_currentTick) * TimerInterval / 1000.0,
-                                double(m_expectedTime));
-    const double progress = ProgressResolution * 2 * mapped / M_PI;
-    m_futureInterface.setProgressValue(ProgressResolution * m_currentProgress + progress);
+    const int halfLife = qRound(1000.0 * m_expectedTime / TimerInterval);
+    const int pMin = ProgressResolution * m_currentProgress;
+    const int pMax = ProgressResolution * (m_currentProgress + 1);
+    const int newValue = MathUtils::interpolateTangential(m_currentTick, halfLife, pMin, pMax);
+    m_futureInterface.setProgressValue(newValue);
 }
 
 /*!
diff --git a/src/plugins/diffeditor/sidebysidediffeditorwidget.cpp b/src/plugins/diffeditor/sidebysidediffeditorwidget.cpp
index 70d9e2ee55..010f656be8 100644
--- a/src/plugins/diffeditor/sidebysidediffeditorwidget.cpp
+++ b/src/plugins/diffeditor/sidebysidediffeditorwidget.cpp
@@ -365,7 +365,7 @@ SideBySideDiffOutput SideDiffData::diffOutput(QFutureInterface<void> &fi, int pr
         diffText[RightSide].replace('\r', ' ');
         output.side[LeftSide].diffText += diffText[LeftSide];
         output.side[RightSide].diffText += diffText[RightSide];
-        fi.setProgressValue(MathUtils::interpolate(++i, 0, count, progressMin, progressMax));
+        fi.setProgressValue(MathUtils::interpolateLinear(++i, 0, count, progressMin, progressMax));
         if (fi.isCanceled())
             return {};
     }
@@ -952,7 +952,7 @@ void SideBySideDiffEditorWidget::showDiff()
                 const QString package = output.side[side].diffText.mid(currentPos, packageSize);
                 cursor.insertText(package);
                 currentPos += package.size();
-                fi.setProgressValue(MathUtils::interpolate(currentPos, 0, diffSize, progressMin, progressMax));
+                fi.setProgressValue(MathUtils::interpolateLinear(currentPos, 0, diffSize, progressMin, progressMax));
                 if (fi.isCanceled())
                     return;
             }
diff --git a/src/plugins/diffeditor/unifieddiffeditorwidget.cpp b/src/plugins/diffeditor/unifieddiffeditorwidget.cpp
index c082db78ec..6e8abb9c24 100644
--- a/src/plugins/diffeditor/unifieddiffeditorwidget.cpp
+++ b/src/plugins/diffeditor/unifieddiffeditorwidget.cpp
@@ -436,7 +436,7 @@ UnifiedDiffOutput UnifiedDiffData::diffOutput(QFutureInterface<void> &fi, int pr
                     output.diffData.m_chunkInfo.setChunkIndex(oldBlock, blockNumber - oldBlock, j);
             }
         }
-        fi.setProgressValue(MathUtils::interpolate(++i, 0, count, progressMin, progressMax));
+        fi.setProgressValue(MathUtils::interpolateLinear(++i, 0, count, progressMin, progressMax));
         if (fi.isCanceled())
             return {};
     }
@@ -511,7 +511,7 @@ void UnifiedDiffEditorWidget::showDiff()
             const QString package = output.diffText.mid(currentPos, packageSize);
             cursor.insertText(package);
             currentPos += package.size();
-            fi.setProgressValue(MathUtils::interpolate(currentPos, 0, diffSize, firstPartMax, progressMax));
+            fi.setProgressValue(MathUtils::interpolateLinear(currentPos, 0, diffSize, firstPartMax, progressMax));
             if (futureInterface.isCanceled())
                 return;
         }
diff --git a/tests/auto/utils/CMakeLists.txt b/tests/auto/utils/CMakeLists.txt
index ee2f8e475a..34532e8f91 100644
--- a/tests/auto/utils/CMakeLists.txt
+++ b/tests/auto/utils/CMakeLists.txt
@@ -6,6 +6,7 @@ add_subdirectory(fileutils)
 add_subdirectory(fsengine)
 add_subdirectory(fuzzymatcher)
 add_subdirectory(indexedcontainerproxyconstiterator)
+add_subdirectory(mathutils)
 add_subdirectory(multicursor)
 add_subdirectory(persistentsettings)
 add_subdirectory(qtcprocess)
diff --git a/tests/auto/utils/mathutils/CMakeLists.txt b/tests/auto/utils/mathutils/CMakeLists.txt
new file mode 100644
index 0000000000..d2ec2d5194
--- /dev/null
+++ b/tests/auto/utils/mathutils/CMakeLists.txt
@@ -0,0 +1,4 @@
+add_qtc_test(tst_utils_mathutils
+  DEPENDS Utils
+  SOURCES tst_mathutils.cpp
+)
diff --git a/tests/auto/utils/mathutils/mathutils.qbs b/tests/auto/utils/mathutils/mathutils.qbs
new file mode 100644
index 0000000000..36fa42ffc4
--- /dev/null
+++ b/tests/auto/utils/mathutils/mathutils.qbs
@@ -0,0 +1,7 @@
+import qbs
+
+QtcAutotest {
+    name: "MathUtils autotest"
+    Depends { name: "Utils" }
+    files: "tst_mathutils.cpp"
+}
diff --git a/tests/auto/utils/mathutils/tst_mathutils.cpp b/tests/auto/utils/mathutils/tst_mathutils.cpp
new file mode 100644
index 0000000000..30d2d8d6c5
--- /dev/null
+++ b/tests/auto/utils/mathutils/tst_mathutils.cpp
@@ -0,0 +1,77 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#include "utils/mathutils.h"
+
+#include <QtTest>
+
+using namespace Utils;
+
+class tst_MathUtils : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void interpolateLinear_data();
+    void interpolateLinear();
+    void interpolateTangential_data();
+    void interpolateTangential();
+};
+
+void tst_MathUtils::interpolateLinear_data()
+{
+    QTest::addColumn<int>("x");
+    QTest::addColumn<int>("x1");
+    QTest::addColumn<int>("x2");
+    QTest::addColumn<int>("y1");
+    QTest::addColumn<int>("y2");
+    QTest::addColumn<int>("result");
+
+    QTest::newRow("x1") << 2 << 2 << 8 << 10 << 20 << 10;
+    QTest::newRow("middleValue") << 5 << 2 << 8 << 10 << 20 << 15;
+    QTest::newRow("x2") << 8 << 2 << 8 << 10 << 20 << 20;
+    QTest::newRow("belowX1") << -1 << 2 << 8 << 10 << 20 << 5;
+    QTest::newRow("aboveX2") << 11 << 2 << 8 << 10 << 20 << 25;
+}
+
+void tst_MathUtils::interpolateLinear()
+{
+    QFETCH(int, x);
+    QFETCH(int, x1);
+    QFETCH(int, x2);
+    QFETCH(int, y1);
+    QFETCH(int, y2);
+    QFETCH(int, result);
+
+    const int y = MathUtils::interpolateLinear(x, x1, x2, y1, y2);
+    QCOMPARE(y, result);
+}
+
+void tst_MathUtils::interpolateTangential_data()
+{
+    QTest::addColumn<int>("x");
+    QTest::addColumn<int>("xHalfLife");
+    QTest::addColumn<int>("y1");
+    QTest::addColumn<int>("y2");
+    QTest::addColumn<int>("result");
+
+    QTest::newRow("zero") << 0 << 8 << 10 << 20 << 10;
+    QTest::newRow("halfLife") << 8 << 8 << 10 << 20 << 15;
+    QTest::newRow("approxInfinity") << 1000 << 8 << 10 << 20 << 20;
+}
+
+void tst_MathUtils::interpolateTangential()
+{
+    QFETCH(int, x);
+    QFETCH(int, xHalfLife);
+    QFETCH(int, y1);
+    QFETCH(int, y2);
+    QFETCH(int, result);
+
+    const int y = MathUtils::interpolateTangential(x, xHalfLife, y1, y2);
+    QCOMPARE(y, result);
+}
+
+QTEST_GUILESS_MAIN(tst_MathUtils)
+
+#include "tst_mathutils.moc"
diff --git a/tests/auto/utils/utils.qbs b/tests/auto/utils/utils.qbs
index 327d35d607..138b1b72ed 100644
--- a/tests/auto/utils/utils.qbs
+++ b/tests/auto/utils/utils.qbs
@@ -11,6 +11,7 @@ Project {
         "fsengine/fsengine.qbs",
         "fuzzymatcher/fuzzymatcher.qbs",
         "indexedcontainerproxyconstiterator/indexedcontainerproxyconstiterator.qbs",
+        "mathutils/mathutils.qbs",
         "multicursor/multicursor.qbs",
         "persistentsettings/persistentsettings.qbs",
         "qtcprocess/qtcprocess.qbs",