ruler_item.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2017-2021 Kicad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <preview_items/ruler_item.h>
#include <preview_items/preview_utils.h>
#include <gal/graphics_abstraction_layer.h>
#include <layer_ids.h>
#include <painter.h>
#include <view/view.h>
#include <trigo.h>

using namespace KIGFX::PREVIEW;

static const double maxTickDensity = 10.0; // min pixels between tick marks
static const double midTickLengthFactor = 1.5;
static const double majorTickLengthFactor = 2.5;


/*
 * It would be nice to know why Cairo seems to have an opposite layer order from GAL, but
 * only when drawing RULER_ITEMs (the TWO_POINT_ASSISTANT and ARC_ASSISTANT are immune from
 * this issue).
 *
 * Until then, this egregious hack...
 */
static int getShadowLayer( KIGFX::GAL* aGal )
{
 if( aGal->IsCairoEngine() )
 return LAYER_SELECT_OVERLAY;
 else
 return LAYER_GP_OVERLAY;
}


static void drawCursorStrings( KIGFX::VIEW* aView, const VECTOR2D& aCursor,
 const VECTOR2D& aRulerVec, EDA_UNITS aUnits,
 bool aDrawingDropShadows, bool aFlipX, bool aFlipY )
{
 // draw the cursor labels
 std::vector<wxString> cursorStrings;

 VECTOR2D temp = aRulerVec;

 if( aFlipX )
 temp.x = -temp.x;

 if( aFlipY )
 temp.y = -temp.y;

 cursorStrings.push_back( DimensionLabel( wxT( "x" ), temp.x, aUnits ) );
 cursorStrings.push_back( DimensionLabel( wxT( "y" ), temp.y, aUnits ) );

 cursorStrings.push_back( DimensionLabel( wxT( "r" ), aRulerVec.EuclideanNorm(), aUnits ) );

 double degs = RAD2DECIDEG( -aRulerVec.Angle() );
 cursorStrings.push_back( DimensionLabel( wxString::FromUTF8( "θ" ), degs,
 EDA_UNITS::DEGREES ) );

 temp = aRulerVec;
 DrawTextNextToCursor( aView, aCursor, -temp, cursorStrings, aDrawingDropShadows );
}


static double getTickLineWidth( const TEXT_DIMS& textDims, bool aDrawingDropShadows )
{
 double width = textDims.StrokeWidth * 0.8;

 if( aDrawingDropShadows )
 width += textDims.ShadowWidth;

 return width;
}


struct TICK_FORMAT
{
 double divisionBase; 
 int majorStep; 
 int midStep; 
};


static TICK_FORMAT getTickFormatForScale( double aScale, double& aTickSpace, EDA_UNITS aUnits )
{
 // simple 1/2/5 scales per decade
 static std::vector<TICK_FORMAT> tickFormats =
 {
 { 2, 10, 5 }, // |....:....|
 { 2, 5, 0 }, // |....|
 { 2.5, 2, 0 }, // |.|.|
 };

 // could start at a set number of MM, but that's not available in common
 aTickSpace = 1;

 // Convert to a round (mod-10) number of mils for imperial units
 if( EDA_UNIT_UTILS::IsImperialUnit( aUnits ) )
 aTickSpace *= 2.54;

 int tickFormat = 0;

 while( true )
 {
 const auto pixelSpace = aTickSpace * aScale;

 if( pixelSpace >= maxTickDensity )
 break;

 tickFormat = ( tickFormat + 1 ) % tickFormats.size();
 aTickSpace *= tickFormats[tickFormat].divisionBase;
 }

 return tickFormats[tickFormat];
}


void drawTicksAlongLine( KIGFX::VIEW* aView, const VECTOR2D& aOrigin, const VECTOR2D& aLine,
 double aMinorTickLen, EDA_UNITS aUnits, bool aDrawingDropShadows )
{
 KIGFX::GAL* gal = aView->GetGAL();
 VECTOR2D tickLine = aLine.Rotate( -M_PI_2 );
 double tickSpace;
 TICK_FORMAT tickF = getTickFormatForScale( gal->GetWorldScale(), tickSpace, aUnits );

 // number of ticks in whole ruler
 int numTicks = (int) std::ceil( aLine.EuclideanNorm() / tickSpace );

 // work out which way up the tick labels go
 TEXT_DIMS textDims = SetConstantGlyphHeight( gal, -1 );
 double textThickness = textDims.StrokeWidth;
 double labelAngle = -tickLine.Angle();
 double textOffset = 0;

 if( aDrawingDropShadows )
 {
 textOffset = textDims.ShadowWidth;
 textThickness += 2 * textDims.ShadowWidth;
 }

 double majorTickLen = aMinorTickLen * ( majorTickLengthFactor + 1 );
 VECTOR2D labelOffset = tickLine.Resize( majorTickLen - textOffset );

 if( aView->IsMirroredX() )
 {
 textOffset = -textOffset;
 labelOffset = -labelOffset;
 }

 if( aLine.Angle() > 0 )
 {
 gal->SetHorizontalJustify( GR_TEXT_HJUSTIFY_LEFT );
 }
 else
 {
 gal->SetHorizontalJustify( GR_TEXT_HJUSTIFY_RIGHT );
 labelAngle += M_PI;
 }

 BOX2D viewportD = aView->GetViewport();
 BOX2I viewport( VECTOR2I( viewportD.GetPosition() ), VECTOR2I( viewportD.GetSize() ) );

 viewport.Inflate( majorTickLen * 2 ); // Doesn't have to be accurate, just big enough not
 // to exclude anything that should be partially drawn

 for( int i = 0; i < numTicks; ++i )
 {
 const VECTOR2D tickPos = aOrigin + aLine.Resize( tickSpace * i );

 if( !viewport.Contains( tickPos ) )
 continue;

 double length = aMinorTickLen;
 bool drawLabel = false;

 if( i % tickF.majorStep == 0 )
 {
 drawLabel = true;
 length *= majorTickLengthFactor;
 }
 else if( tickF.midStep && i % tickF.midStep == 0 )
 {
 drawLabel = true;
 length *= midTickLengthFactor;
 }

 gal->SetLineWidth( textThickness / 2 );
 gal->DrawLine( tickPos, tickPos + tickLine.Resize( length ) );

 if( drawLabel )
 {
 wxString label = DimensionLabel( wxEmptyString, tickSpace * i, aUnits, false );
 gal->SetLineWidth( textThickness );
 gal->StrokeText( label, tickPos + labelOffset, labelAngle );
 }
 }
}


void drawBacksideTicks( KIGFX::VIEW* aView, const VECTOR2D& aOrigin, const VECTOR2D& aLine,
 double aTickLen, int aNumDivisions, bool aDrawingDropShadows )
{
 KIGFX::GAL* gal = aView->GetGAL();
 const double backTickSpace = aLine.EuclideanNorm() / aNumDivisions;
 const VECTOR2D backTickVec = aLine.Rotate( M_PI_2 ).Resize( aTickLen );
 TEXT_DIMS textDims = SetConstantGlyphHeight( gal, -1 );

 BOX2D viewportD = aView->GetViewport();
 BOX2I viewport( VECTOR2I( viewportD.GetPosition() ), VECTOR2I( viewportD.GetSize() ) );

 viewport.Inflate( aTickLen * 4 ); // Doesn't have to be accurate, just big enough not to
 // exclude anything that should be partially drawn

 for( int i = 0; i < aNumDivisions + 1; ++i )
 {
 const VECTOR2D backTickPos = aOrigin + aLine.Resize( backTickSpace * i );

 if( !viewport.Contains( backTickPos ) )
 continue;

 gal->SetLineWidth( getTickLineWidth( textDims, aDrawingDropShadows ) );
 gal->DrawLine( backTickPos, backTickPos + backTickVec );
 }
}


RULER_ITEM::RULER_ITEM( const TWO_POINT_GEOMETRY_MANAGER& aGeomMgr, EDA_UNITS userUnits,
 bool aFlipX, bool aFlipY )
 : EDA_ITEM( NOT_USED ), // Never added to anything - just a preview
 m_geomMgr( aGeomMgr ),
 m_userUnits( userUnits ),
 m_flipX( aFlipX ),
 m_flipY( aFlipY )
{
}


const BOX2I RULER_ITEM::ViewBBox() const
{
 BOX2I tmp;

 if( m_geomMgr.GetOrigin() == m_geomMgr.GetEnd() )
 return tmp;

 // this is an edit-time artefact; no reason to try and be smart with the bounding box
 // (besides, we can't tell the text extents without a view to know what the scale is)
 tmp.SetMaximum();
 return tmp;
}


void RULER_ITEM::ViewGetLayers( int aLayers[], int& aCount ) const
{
 aLayers[0] = LAYER_SELECT_OVERLAY;
 aLayers[1] = LAYER_GP_OVERLAY;
 aCount = 2;
}


void RULER_ITEM::ViewDraw( int aLayer, KIGFX::VIEW* aView ) const
{
 KIGFX::GAL* gal = aView->GetGAL();
 RENDER_SETTINGS* rs = aView->GetPainter()->GetSettings();
 bool drawingDropShadows = ( aLayer == getShadowLayer( gal ) );

 gal->PushDepth();
 gal->SetLayerDepth( gal->GetMinDepth() );

 VECTOR2D origin = m_geomMgr.GetOrigin();
 VECTOR2D end = m_geomMgr.GetEnd();

 gal->SetIsStroke( true );
 gal->SetIsFill( false );

 gal->SetTextMirrored( false );
 gal->SetStrokeColor( rs->GetLayerColor( LAYER_AUX_ITEMS ) );

 if( drawingDropShadows )
 gal->SetStrokeColor( GetShadowColor( gal->GetStrokeColor() ) );

 gal->ResetTextAttributes();
 TEXT_DIMS textDims = SetConstantGlyphHeight( gal );

 // draw the main line from the origin to cursor
 gal->SetLineWidth( getTickLineWidth( textDims, drawingDropShadows ) );
 gal->DrawLine( origin, end );

 VECTOR2D rulerVec( end - origin );

 drawCursorStrings( aView, end, rulerVec, m_userUnits, drawingDropShadows, m_flipX, m_flipY );

 // basic tick size
 const double minorTickLen = 5.0 / gal->GetWorldScale();
 const double majorTickLen = minorTickLen * majorTickLengthFactor;

 drawTicksAlongLine( aView, origin, rulerVec, minorTickLen, m_userUnits, drawingDropShadows );

 drawBacksideTicks( aView, origin, rulerVec, majorTickLen, 2, drawingDropShadows );

 // draw the back of the origin "crosshair"
 gal->DrawLine( origin, origin + rulerVec.Resize( -minorTickLen * midTickLengthFactor ) );
 gal->PopDepth();
}