1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "config.h"
32#include "PlatformThemeChromiumGtk.h"
33
34namespace WebCore {
35
36unsigned PlatformThemeChromiumGtk::s_thumbInactiveColor = 0xeaeaea;
37unsigned PlatformThemeChromiumGtk::s_thumbActiveColor = 0xf4f4f4;
38unsigned PlatformThemeChromiumGtk::s_trackColor = 0xd3d3d3;
39
40void PlatformThemeChromiumGtk::setScrollbarColors(
41    SkColor inactiveColor, SkColor activeColor, SkColor trackColor)
42{
43    s_thumbInactiveColor = inactiveColor;
44    s_thumbActiveColor = activeColor;
45    s_trackColor = trackColor;
46}
47
48static SkScalar clamp(SkScalar value, SkScalar min, SkScalar max)
49{
50    return std::min(std::max(value, min), max);
51}
52
53SkColor PlatformThemeChromiumGtk::saturateAndBrighten(const SkScalar hsv[3], SkScalar saturateAmount, SkScalar brightenAmount)
54{
55    SkScalar color[3];
56    color[0] = hsv[0];
57    color[1] = clamp(hsv[1] + saturateAmount, 0.0, 1.0);
58    color[2] = clamp(hsv[2] + brightenAmount, 0.0, 1.0);
59    return SkHSVToColor(color);
60}
61
62SkColor PlatformThemeChromiumGtk::outlineColor(const SkScalar hsv1[3], const SkScalar hsv2[3])
63{
64    // GTK Theme engines have way too much control over the layout of
65    // the scrollbar. We might be able to more closely approximate its
66    // look-and-feel, if we sent whole images instead of just colors
67    // from the browser to the renderer. But even then, some themes
68    // would just break.
69    //
70    // So, instead, we don't even try to 100% replicate the look of
71    // the native scrollbar. We render our own version, but we make
72    // sure to pick colors that blend in nicely with the system GTK
73    // theme. In most cases, we can just sample a couple of pixels
74    // from the system scrollbar and use those colors to draw our
75    // scrollbar.
76    //
77    // This works fine for the track color and the overall thumb
78    // color. But it fails spectacularly for the outline color used
79    // around the thumb piece.  Not all themes have a clearly defined
80    // outline. For some of them it is partially transparent, and for
81    // others the thickness is very unpredictable.
82    //
83    // So, instead of trying to approximate the system theme, we
84    // instead try to compute a reasonable looking choice based on the
85    // known color of the track and the thumb piece. This is difficult
86    // when trying to deal both with high- and low-contrast themes,
87    // and both with positive and inverted themes.
88    //
89    // The following code has been tested to look OK with all of the
90    // default GTK themes.
91    SkScalar minDiff = clamp((hsv1[1] + hsv2[1]) * 1.2, 0.28, 0.5);
92    SkScalar diff = clamp(fabs(hsv1[2] - hsv2[2]) / 2, minDiff, 0.5);
93
94    if (hsv1[2] + hsv2[2] > 1.0)
95        diff = -diff;
96
97    return saturateAndBrighten(hsv2, -0.2, diff);
98}
99
100void PlatformThemeChromiumGtk::paintArrowButton(GraphicsContext* gc, const IntRect& rect, ArrowDirection direction, ControlStates states)
101{
102    SkCanvas* const canvas = gc->platformContext()->canvas();
103    int widthMiddle, lengthMiddle;
104    SkPaint paint;
105    if (direction == North || direction == South) {
106        widthMiddle = rect.width() / 2 + 1;
107        lengthMiddle = rect.height() / 2 + 1;
108    } else {
109        lengthMiddle = rect.width() / 2 + 1;
110        widthMiddle = rect.height() / 2 + 1;
111    }
112
113    // Calculate button color.
114    SkScalar trackHSV[3];
115    SkColorToHSV(trackColor(), trackHSV);
116    SkColor buttonColor = saturateAndBrighten(trackHSV, 0, 0.2);
117    SkColor backgroundColor = buttonColor;
118    if (states & PressedState) {
119        SkScalar buttonHSV[3];
120        SkColorToHSV(buttonColor, buttonHSV);
121        buttonColor = saturateAndBrighten(buttonHSV, 0, -0.1);
122    } else if (states & HoverState) {
123        SkScalar buttonHSV[3];
124        SkColorToHSV(buttonColor, buttonHSV);
125        buttonColor = saturateAndBrighten(buttonHSV, 0, 0.05);
126    }
127
128    SkIRect skrect;
129    skrect.set(rect.x(), rect.y(), rect.x() + rect.width(), rect.y() + rect.height());
130    // Paint the background (the area visible behind the rounded corners).
131    paint.setColor(backgroundColor);
132    canvas->drawIRect(skrect, paint);
133
134    // Paint the button's outline and fill the middle
135    SkPath outline;
136    switch (direction) {
137    case North:
138        outline.moveTo(rect.x() + 0.5, rect.y() + rect.height() + 0.5);
139        outline.rLineTo(0, -(rect.height() - 2));
140        outline.rLineTo(2, -2);
141        outline.rLineTo(rect.width() - 5, 0);
142        outline.rLineTo(2, 2);
143        outline.rLineTo(0, rect.height() - 2);
144        break;
145    case South:
146        outline.moveTo(rect.x() + 0.5, rect.y() - 0.5);
147        outline.rLineTo(0, rect.height() - 2);
148        outline.rLineTo(2, 2);
149        outline.rLineTo(rect.width() - 5, 0);
150        outline.rLineTo(2, -2);
151        outline.rLineTo(0, -(rect.height() - 2));
152        break;
153    case East:
154        outline.moveTo(rect.x() - 0.5, rect.y() + 0.5);
155        outline.rLineTo(rect.width() - 2, 0);
156        outline.rLineTo(2, 2);
157        outline.rLineTo(0, rect.height() - 5);
158        outline.rLineTo(-2, 2);
159        outline.rLineTo(-(rect.width() - 2), 0);
160        break;
161    case West:
162        outline.moveTo(rect.x() + rect.width() + 0.5, rect.y() + 0.5);
163        outline.rLineTo(-(rect.width() - 2), 0);
164        outline.rLineTo(-2, 2);
165        outline.rLineTo(0, rect.height() - 5);
166        outline.rLineTo(2, 2);
167        outline.rLineTo(rect.width() - 2, 0);
168        break;
169    }
170    outline.close();
171
172    paint.setStyle(SkPaint::kFill_Style);
173    paint.setColor(buttonColor);
174    canvas->drawPath(outline, paint);
175
176    paint.setAntiAlias(true);
177    paint.setStyle(SkPaint::kStroke_Style);
178    SkScalar thumbHSV[3];
179    SkColorToHSV(thumbInactiveColor(), thumbHSV);
180    paint.setColor(outlineColor(trackHSV, thumbHSV));
181    canvas->drawPath(outline, paint);
182
183    // If the button is disabled or read-only, the arrow is drawn with the outline color.
184    if (states & EnabledState && !(states & ReadOnlyState))
185        paint.setColor(SK_ColorBLACK);
186
187    paint.setAntiAlias(false);
188    paint.setStyle(SkPaint::kFill_Style);
189
190    SkPath path;
191    // The constants in this block of code are hand-tailored to produce good
192    // looking arrows without anti-aliasing.
193    switch (direction) {
194    case North:
195        path.moveTo(rect.x() + widthMiddle - 4, rect.y() + lengthMiddle + 2);
196        path.rLineTo(7, 0);
197        path.rLineTo(-4, -4);
198        break;
199    case South:
200        path.moveTo(rect.x() + widthMiddle - 4, rect.y() + lengthMiddle - 3);
201        path.rLineTo(7, 0);
202        path.rLineTo(-4, 4);
203        break;
204    case East:
205        path.moveTo(rect.x() + lengthMiddle - 3, rect.y() + widthMiddle - 4);
206        path.rLineTo(0, 7);
207        path.rLineTo(4, -4);
208        break;
209    case West:
210        path.moveTo(rect.x() + lengthMiddle + 1, rect.y() + widthMiddle - 5);
211        path.rLineTo(0, 9);
212        path.rLineTo(-4, -4);
213        break;
214    }
215    path.close();
216
217    canvas->drawPath(path, paint);
218}
219
220} // namespace WebCore
221
222