libs/hwui/utils/TestUtils.cpp

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "TestUtils.h"

namespace android {
namespace uirenderer {

SkColor TestUtils::interpolateColor(float fraction, SkColor start, SkColor end) {
    int startA = (start >> 24) & 0xff;
    int startR = (start >> 16) & 0xff;
    int startG = (start >> 8) & 0xff;
    int startB = start & 0xff;

    int endA = (end >> 24) & 0xff;
    int endR = (end >> 16) & 0xff;
    int endG = (end >> 8) & 0xff;
    int endB = end & 0xff;

    return (int)((startA + (int)(fraction * (endA - startA))) << 24)
            | (int)((startR + (int)(fraction * (endR - startR))) << 16)
            | (int)((startG + (int)(fraction * (endG - startG))) << 8)
            | (int)((startB + (int)(fraction * (endB - startB))));
}

void TestUtils::drawTextToCanvas(TestCanvas* canvas, const char* text,
        const SkPaint& paint, float x, float y) {
    // drawing text requires GlyphID TextEncoding (which JNI layer would have done)
    LOG_ALWAYS_FATAL_IF(paint.getTextEncoding() != SkPaint::kGlyphID_TextEncoding,
            "must use glyph encoding");

    SkMatrix identity;
    identity.setIdentity();
    SkSurfaceProps surfaceProps(0, kUnknown_SkPixelGeometry);
    SkAutoGlyphCacheNoGamma autoCache(paint, &surfaceProps, &identity);

    float totalAdvance = 0;
    std::vector<glyph_t> glyphs;
    std::vector<float> positions;
    Rect bounds;
    while (*text != '\0') {
        SkUnichar unichar = SkUTF8_NextUnichar(&text);
        glyph_t glyph = autoCache.getCache()->unicharToGlyph(unichar);
        autoCache.getCache()->unicharToGlyph(unichar);

        // push glyph and its relative position
        glyphs.push_back(glyph);
        positions.push_back(totalAdvance);
        positions.push_back(0);

        // compute bounds
        SkGlyph skGlyph = autoCache.getCache()->getUnicharMetrics(unichar);
        Rect glyphBounds(skGlyph.fWidth, skGlyph.fHeight);
        glyphBounds.translate(totalAdvance + skGlyph.fLeft, skGlyph.fTop);
        bounds.unionWith(glyphBounds);

        // advance next character
        SkScalar skWidth;
        paint.getTextWidths(&glyph, sizeof(glyph), &skWidth, NULL);
        totalAdvance += skWidth;
    }

    // apply alignment via x parameter (which JNI layer would have done)
    if (paint.getTextAlign() == SkPaint::kCenter_Align) {
        x -= totalAdvance / 2;
    } else if (paint.getTextAlign() == SkPaint::kRight_Align) {
        x -= totalAdvance;
    }

    bounds.translate(x, y);

    // Force left alignment, since alignment offset is already baked in
    SkPaint alignPaintCopy(paint);
    alignPaintCopy.setTextAlign(SkPaint::kLeft_Align);
    canvas->drawText(glyphs.data(), positions.data(), glyphs.size(), alignPaintCopy, x, y,
                bounds.left, bounds.top, bounds.right, bounds.bottom, totalAdvance);
}

} /* namespace uirenderer */
} /* namespace android */