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[poincare/zoom] Preserve standard bound when normalizing

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Change-Id: I6d736e945eda6982ad26836763feded8a55134a0
This commit is contained in:
Gabriel Ozouf
2020-11-17 11:37:44 +01:00
committed by EmilieNumworks
parent e4162976e4
commit 540209f1a9
1 changed files with 30 additions and 18 deletions
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48
poincare/src/zoom.cpp
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@@ -221,36 +221,37 @@ void Zoom::RefinedYRangeForDisplay(ValueAtAbscissa evaluation, float xMin, float
}
}
static float smoothToPowerOfTen(float x) {
return std::pow(10.f, std::round(std::log10(x)));
}
void Zoom::RangeWithRatioForDisplay(ValueAtAbscissa evaluation, float yxRatio, float * xMin, float * xMax, float * yMin, float * yMax, Context * context, const void * auxiliary) {
constexpr float units[] = {k_smallUnitMantissa, k_mediumUnitMantissa, k_largeUnitMantissa};
constexpr float rangeMagnitudeWeight = 0.2f;
constexpr float maxMagnitudeDifference = 2.f;
/* RefinedYRange for display, by default, evaluates the function 80 times,
* and we call it 21 times. As we only need a rough estimate of the range to
* compare it to the others, we save some time by only sampling the function
* 20 times. */
constexpr int sampleSize = k_sampleSize / 4;
float bestGrade = FLT_MAX;
float bestGrade = FLT_MAX, bestUnit, bestMagnitude;
float unit = k_smallUnitMantissa;
float xMagnitude = k_minimalDistance;
float yMinRange = FLT_MAX, yMaxRange = -FLT_MAX;
while (xMagnitude < k_maximalDistance) {
for(const float unit : units) {
const float xRange = unit * xMagnitude;
RefinedYRangeForDisplay(evaluation, -xRange, xRange, &yMinRange, &yMaxRange, context, auxiliary, sampleSize);
float currentRatio = (yMaxRange - yMinRange) / (2 * xRange);
float grade = std::fabs(std::log(currentRatio / yxRatio));
/* When in doubt, favor ranges between [-1, 1] and [-10, 10] */
grade += std::fabs(std::log(xRange / 10.f) * std::log(xRange)) * rangeMagnitudeWeight;
if (std::fabs(std::log(currentRatio / yxRatio)) < maxMagnitudeDifference && grade < bestGrade) {
bestGrade = grade;
*xMin = -xRange;
*xMax = xRange;
*yMin = yMinRange;
*yMax = yMaxRange;
}
const float xRange = unit * xMagnitude;
RefinedYRangeForDisplay(evaluation, -xRange, xRange, &yMinRange, &yMaxRange, context, auxiliary, sampleSize);
float currentRatio = (yMaxRange - yMinRange) / (2 * xRange);
float grade = std::fabs(std::log(currentRatio / yxRatio));
/* When in doubt, favor ranges between [-1, 1] and [-10, 10] */
grade += std::fabs(std::log(xRange / 10.f) * std::log(xRange)) * rangeMagnitudeWeight;
if (std::fabs(std::log(currentRatio / yxRatio)) < maxMagnitudeDifference && grade < bestGrade) {
bestGrade = grade;
bestUnit = unit;
bestMagnitude = xMagnitude;
*yMin = yMinRange;
*yMax = yMaxRange;
}
xMagnitude *= 10.f;
NextUnit(&unit, &xMagnitude);
}
if (bestGrade == FLT_MAX) {
*xMin = NAN;
@@ -260,6 +261,17 @@ void Zoom::RangeWithRatioForDisplay(ValueAtAbscissa evaluation, float yxRatio, f
return;
}
/* The X bounds are preset, user-friendly values : we do not want them to be
* altered by the normalization. To that end, we use a larger unit for the
* horizontal axis, so that the Y axis is the one that will be extended. */
float xRange = bestUnit * bestMagnitude;
while ((*yMax - *yMin) / (2 * xRange) > yxRatio) {
NextUnit(&bestUnit, &bestMagnitude);
xRange = bestUnit * bestMagnitude;
}
xRange = bestUnit * smoothToPowerOfTen(bestMagnitude);
*xMin = -xRange;
*xMax = xRange;
SetToRatio(yxRatio, xMin, xMax, yMin, yMax);
}