/*

 * Copyright (C) 2010 Google Inc. All rights reserved.

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 * modification, are permitted provided that the following conditions are

 * met:

 *

 *     * Redistributions of source code must retain the above copyright

 * notice, this list of conditions and the following disclaimer.

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 * in the documentation and/or other materials provided with the

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 * contributors may be used to endorse or promote products derived from

 * this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

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 */

#include "config.h"

#include "PlatformThemeChromiumGtk.h"

namespace WebCore {

unsigned PlatformThemeChromiumGtk::s_thumbInactiveColor = 0xeaeaea;

unsigned PlatformThemeChromiumGtk::s_thumbActiveColor = 0xf4f4f4;

unsigned PlatformThemeChromiumGtk::s_trackColor = 0xd3d3d3;

void PlatformThemeChromiumGtk::setScrollbarColors(

    SkColor inactiveColor, SkColor activeColor, SkColor trackColor)

{

    s_thumbInactiveColor = inactiveColor;

    s_thumbActiveColor = activeColor;

    s_trackColor = trackColor;

}

static SkScalar clamp(SkScalar value, SkScalar min, SkScalar max)

{

    return std::min(std::max(value, min), max);

}

SkColor PlatformThemeChromiumGtk::saturateAndBrighten(const SkScalar hsv[3], SkScalar saturateAmount, SkScalar brightenAmount)

{

    SkScalar color[3];

    color[0] = hsv[0];

    color[1] = clamp(hsv[1] + saturateAmount, 0.0, 1.0);

    color[2] = clamp(hsv[2] + brightenAmount, 0.0, 1.0);

    return SkHSVToColor(color);

}

SkColor PlatformThemeChromiumGtk::outlineColor(const SkScalar hsv1[3], const SkScalar hsv2[3])

{

    // GTK Theme engines have way too much control over the layout of

    // the scrollbar. We might be able to more closely approximate its

    // look-and-feel, if we sent whole images instead of just colors

    // from the browser to the renderer. But even then, some themes

    // would just break.

    //

    // So, instead, we don't even try to 100% replicate the look of

    // the native scrollbar. We render our own version, but we make

    // sure to pick colors that blend in nicely with the system GTK

    // theme. In most cases, we can just sample a couple of pixels

    // from the system scrollbar and use those colors to draw our

    // scrollbar.

    //

    // This works fine for the track color and the overall thumb

    // color. But it fails spectacularly for the outline color used

    // around the thumb piece.  Not all themes have a clearly defined

    // outline. For some of them it is partially transparent, and for

    // others the thickness is very unpredictable.

    //

    // So, instead of trying to approximate the system theme, we

    // instead try to compute a reasonable looking choice based on the

    // known color of the track and the thumb piece. This is difficult

    // when trying to deal both with high- and low-contrast themes,

    // and both with positive and inverted themes.

    //

    // The following code has been tested to look OK with all of the

    // default GTK themes.

    SkScalar minDiff = clamp((hsv1[1] + hsv2[1]) * 1.2, 0.28, 0.5);

    SkScalar diff = clamp(fabs(hsv1[2] - hsv2[2]) / 2, minDiff, 0.5);

    if (hsv1[2] + hsv2[2] > 1.0)

        diff = -diff;

    return saturateAndBrighten(hsv2, -0.2, diff);

}

void PlatformThemeChromiumGtk::paintArrowButton(GraphicsContext* gc, const IntRect& rect, ArrowDirection direction, ControlStates states)

{

    SkCanvas* const canvas = gc->platformContext()->canvas();

    int widthMiddle, lengthMiddle;

    SkPaint paint;

    if (direction == North || direction == South) {

        widthMiddle = rect.width() / 2 + 1;

        lengthMiddle = rect.height() / 2 + 1;

    } else {

        lengthMiddle = rect.width() / 2 + 1;

        widthMiddle = rect.height() / 2 + 1;

    }

    // Calculate button color.

    SkScalar trackHSV[3];

    SkColorToHSV(trackColor(), trackHSV);

    SkColor buttonColor = saturateAndBrighten(trackHSV, 0, 0.2);

    SkColor backgroundColor = buttonColor;

    if (states & PressedState) {

        SkScalar buttonHSV[3];

        SkColorToHSV(buttonColor, buttonHSV);

        buttonColor = saturateAndBrighten(buttonHSV, 0, -0.1);

    } else if (states & HoverState) {

        SkScalar buttonHSV[3];

        SkColorToHSV(buttonColor, buttonHSV);

        buttonColor = saturateAndBrighten(buttonHSV, 0, 0.05);

    }

    SkIRect skrect;

    skrect.set(rect.x(), rect.y(), rect.x() + rect.width(), rect.y() + rect.height());

    // Paint the background (the area visible behind the rounded corners).

    paint.setColor(backgroundColor);

    canvas->drawIRect(skrect, paint);

    // Paint the button's outline and fill the middle

    SkPath outline;

    switch (direction) {

    case North:

        outline.moveTo(rect.x() + 0.5, rect.y() + rect.height() + 0.5);

        outline.rLineTo(0, -(rect.height() - 2));

        outline.rLineTo(2, -2);

        outline.rLineTo(rect.width() - 5, 0);

        outline.rLineTo(2, 2);

        outline.rLineTo(0, rect.height() - 2);

        break;

    case South:

        outline.moveTo(rect.x() + 0.5, rect.y() - 0.5);

        outline.rLineTo(0, rect.height() - 2);

        outline.rLineTo(2, 2);

        outline.rLineTo(rect.width() - 5, 0);

        outline.rLineTo(2, -2);

        outline.rLineTo(0, -(rect.height() - 2));

        break;

    case East:

        outline.moveTo(rect.x() - 0.5, rect.y() + 0.5);

        outline.rLineTo(rect.width() - 2, 0);

        outline.rLineTo(2, 2);

        outline.rLineTo(0, rect.height() - 5);

        outline.rLineTo(-2, 2);

        outline.rLineTo(-(rect.width() - 2), 0);

        break;

    case West:

        outline.moveTo(rect.x() + rect.width() + 0.5, rect.y() + 0.5);

        outline.rLineTo(-(rect.width() - 2), 0);

        outline.rLineTo(-2, 2);

        outline.rLineTo(0, rect.height() - 5);

        outline.rLineTo(2, 2);

        outline.rLineTo(rect.width() - 2, 0);

        break;

    }

    outline.close();

    paint.setStyle(SkPaint::kFill_Style);

    paint.setColor(buttonColor);

    canvas->drawPath(outline, paint);

    paint.setAntiAlias(true);

    paint.setStyle(SkPaint::kStroke_Style);

    SkScalar thumbHSV[3];

    SkColorToHSV(thumbInactiveColor(), thumbHSV);

    paint.setColor(outlineColor(trackHSV, thumbHSV));

    canvas->drawPath(outline, paint);

    // If the button is disabled, the arrow is drawn with the outline color.

    if (states & EnabledState)

        paint.setColor(SK_ColorBLACK);

    paint.setAntiAlias(false);

    paint.setStyle(SkPaint::kFill_Style);

    SkPath path;

    // The constants in this block of code are hand-tailored to produce good

    // looking arrows without anti-aliasing.

    switch (direction) {

    case North:

        path.moveTo(rect.x() + widthMiddle - 4, rect.y() + lengthMiddle + 2);

        path.rLineTo(7, 0);

        path.rLineTo(-4, -4);

        break;

    case South:

        path.moveTo(rect.x() + widthMiddle - 4, rect.y() + lengthMiddle - 3);

        path.rLineTo(7, 0);

        path.rLineTo(-4, 4);

        break;

    case East:

        path.moveTo(rect.x() + lengthMiddle - 3, rect.y() + widthMiddle - 4);

        path.rLineTo(0, 7);

        path.rLineTo(4, -4);

        break;

    case West:

        path.moveTo(rect.x() + lengthMiddle + 1, rect.y() + widthMiddle - 5);

        path.rLineTo(0, 9);

        path.rLineTo(-4, -4);

        break;

    }

    path.close();

    canvas->drawPath(path, paint);

}

} // namespace WebCore